{"product_id":"breast-cancer-during-pregnancy-a-comprehensive-guide-to-diagnosis-treatment-and-safety-for-mother-and-baby","title":"Breast Cancer During Pregnancy: A Comprehensive Guide to Diagnosis, Treatment, and Safety for Mother and Baby","description":"\u003cp\u003eBreast cancer during pregnancy (PrBC) is the most common cancer diagnosed during pregnancy, affecting approximately 1 in 3,000 to 10,000 pregnant women. This patient-friendly article explains that while pregnancy creates unique challenges for cancer diagnosis and treatment, most women (88% in a major international study) can successfully continue their pregnancies while receiving appropriate cancer care. Researchers have found that cancer treatment during pregnancy—including surgery, chemotherapy after the 12th week, and targeted radiation approaches—is generally safe when carefully planned by a multidisciplinary team. Importantly, women with pregnancy-associated breast cancer tend to have more aggressive tumor types, particularly triple-negative breast cancer, but receiving standard treatment during pregnancy rather than delaying delivery or treatment can help avoid complications from premature birth while maintaining comparable outcomes.\u003c\/p\u003e\n\n\u003ch1\u003eBreast Cancer During Pregnancy: A Comprehensive Guide to Diagnosis, Treatment, and Safety for Mother and Baby\u003c\/h1\u003e\n\n\u003ch2\u003eTable of Contents\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"#ddn-key-points\"\u003eKey Points\u003c\/a\u003e\u003c\/li\u003e\n\n  \u003cli\u003e\u003ca href=\"#introduction\"\u003eIntroduction: Why This Research Matters\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#epidemiology\"\u003eHow Common Is Breast Cancer During Pregnancy?\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#presentation\"\u003eRecognizing Symptoms During Pregnancy\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#diagnosis-local\"\u003eDiagnosis: Examining the Breast (Local Staging)\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#diagnosis-distant\"\u003eDiagnosis: Checking for Cancer Spread (Distant Staging)\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#radiation-safety\"\u003eUnderstanding Radiation Risks and Doses\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#pathology\"\u003eTumor Types and Biological Characteristics\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#genetics\"\u003eGenetic Findings in Pregnancy-Associated Breast Cancer\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#treatment-overview\"\u003eTreatment Overview: Balancing Mother and Baby\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#surgery\"\u003eSurgery During Pregnancy\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#sentinel-node\"\u003eSentinel Lymph Node Biopsy: Checking for Lymph Node Spread\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#clinical-implications\"\u003eClinical Implications: What This Means for Patients\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#limitations\"\u003eLimitations of This Research\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#recommendations\"\u003eRecommendations for Patients\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#ddn-faq\"\u003eFrequently Asked Questions\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"#source\"\u003eSource Information\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c!-- ddn:keypoints:start --\u003e\n\u003ch2 id=\"ddn-key-points\"\u003eKey Points\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMost women with breast cancer during pregnancy can safely continue pregnancy while receiving treatment, including surgery and chemotherapy after the first trimester.\u003c\/li\u003e\n\u003cli\u003eIn a large international study, 88% of singleton pregnancies resulted in live birth, but 48% delivered preterm and chemotherapy was linked to more fetal complications.\u003c\/li\u003e\n\u003cli\u003eTermination of pregnancy has not been shown to improve breast cancer outcomes; avoiding treatment delays can reduce risks from premature birth.\u003c\/li\u003e\n\u003cli\u003ePregnant patients more often have aggressive tumor types like triple-negative breast cancer, but treatment follows standard guidelines based on each tumor's biology.\u003c\/li\u003e\n\u003cli\u003eSpecialized multidisciplinary care is essential; endocrine therapy and HER2-targeted therapy are not used during pregnancy, and children exposed to treatment need long-term follow-up.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- ddn:keypoints:end --\u003e\n\n\n\u003ch2 id=\"introduction\"\u003eIntroduction: Why This Research Matters\u003c\/h2\u003e\n\n\u003cp\u003eFinding out you have breast cancer while pregnant is a frightening and overwhelming experience. The good news is that medical knowledge in this area has advanced significantly. This review article, published in \u003cem\u003eBest Practice \u0026amp; Research Clinical Obstetrics and Gynaecology\u003c\/em\u003e, was written by a team of European specialists including medical oncologists, gynecological oncologists, radiation oncologists, surgical oncologists, obstetricians, and pediatric oncologists. They came together to summarize the most current evidence on how to diagnose and treat breast cancer during pregnancy.\u003c\/p\u003e\n\n\u003cp\u003eThe guiding principle is clear: \u003cstrong\u003ewomen should receive state-of-the-art cancer treatment without unnecessary delay, and the pregnancy should be maintained as long as possible\u003c\/strong\u003e—provided it is safe to do so. Treatment decisions should be made by a multidisciplinary team that carefully weighs the selection, sequence, and timing of treatments based on patient factors, tumor characteristics, pregnancy stage, and the patient's own preferences.\u003c\/p\u003e\n\n\u003cp\u003eOne of the most important messages from this research is that \u003cstrong\u003estarting cancer treatment during pregnancy often reduces the risks of early delivery and prematurity\u003c\/strong\u003e. In other words, treating cancer while pregnant can actually protect the baby by allowing the pregnancy to continue closer to full term. The article also describes how specialized teams, such as the multidisciplinary Advisory Board for Cancer in Pregnancy founded in the Netherlands in 2012, can help clinicians make individualized recommendations. These virtual tumor boards include cancer surgeons, gynecological oncologists, obstetric medicine experts, fertility specialists, radiation oncologists, medical oncologists, hematologists, pediatric oncologists, imaging specialists, clinical pharmacologists, and ethicists.\u003c\/p\u003e\n\n\u003ch2 id=\"epidemiology\"\u003eHow Common Is Breast Cancer During Pregnancy?\u003c\/h2\u003e\n\n\u003cp\u003eCancer during pregnancy is rare, occurring in approximately \u003cstrong\u003e1 in 1,000 pregnancies\u003c\/strong\u003e. Among all cancers diagnosed during pregnancy, breast cancer is the most frequent. PrBC is found in \u003cstrong\u003e1 in 3,000 to 10,000 women\u003c\/strong\u003e, which corresponds to about \u003cstrong\u003e2,000 to 4,000 pregnant women in Europe each year\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003cp\u003eThe incidence is likely to rise for two reasons. First, more women are delaying pregnancy to more advanced maternal ages, which increases the background risk of cancer. Second, the wider use of genome-wide non-invasive prenatal testing for fetal chromosome screening will likely lead to incidental discovery of maternal cancers during pregnancy.\u003c\/p\u003e\n\n\u003cp\u003eIn a large cohort study from the International Network on Cancer, Infertility and Pregnancy (INCIP) that included \u003cstrong\u003e1,170 patients over a 20-year period\u003c\/strong\u003e, researchers found that \u003cstrong\u003e67% of patients received cancer treatment during pregnancy\u003c\/strong\u003e, and the likelihood of receiving treatment during pregnancy increased over time—mainly due to increased use of chemotherapy. Overall, \u003cstrong\u003e955 (88%) of 1,089 singleton pregnancies resulted in a live birth\u003c\/strong\u003e, of which 48% were delivered preterm. Over the years, there were more live births and fewer medically induced (iatrogenic) preterm deliveries.\u003c\/p\u003e\n\n\u003cp\u003eHowever, the study also found that exposure to chemotherapy before birth was associated with more fetal complications—specifically, babies who were small for gestational age (smaller than expected for their stage of development) and more frequent admissions to the neonatal intensive care unit (NICU). These findings highlight why careful monitoring and specialized care are essential.\u003c\/p\u003e\n\n\u003cp\u003eTo put breast cancer in younger women in context: among adolescents and young adults (AYA) between ages 15 and 39, breast cancer is the most common cancer diagnosis, with an age-adjusted rate of \u003cstrong\u003e22.9 new cases per 100,000 female AYAs\u003c\/strong\u003e and an age-adjusted death rate of \u003cstrong\u003e2.2 per 100,000 female AYAs\u003c\/strong\u003e. Approximately \u003cstrong\u003e0.2% to 2.6% of all breast cancers occur during pregnancy\u003c\/strong\u003e, while \u003cstrong\u003e35% to 55% of all cases in women under age 45 occur within 5 to 10 years after pregnancy\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003cp\u003eIt is worth clarifying the terminology used in research. The terms \"pregnancy-associated breast cancer\" (PABC) and \"breast cancer during pregnancy\" (PrBC) have historically been used inconsistently. PABC often includes both cancer diagnosed during pregnancy and cancer diagnosed within 6 months to 1 year after delivery. More recently, experts recommend separating these conditions, with postpartum breast cancer (PPBC) potentially extending to 5 to 10 years after birth, as the biology may differ.\u003c\/p\u003e\n\n\u003ch2 id=\"presentation\"\u003eRecognizing Symptoms During Pregnancy\u003c\/h2\u003e\n\n\u003cp\u003ePregnant patients with breast cancer may experience the same symptoms as non-pregnant women, such as a palpable lump or nipple discharge. However, there is often a \u003cstrong\u003edelay in diagnosis\u003c\/strong\u003e because pregnancy causes natural changes in the breasts—including engorgement (swelling from increased blood flow), hypertrophy (enlargement), nipple discharge, and increased density of breast tissue. These normal changes can mask or mimic cancer symptoms.\u003c\/p\u003e\n\n\u003cp\u003eBecause of this delay, women may present with more advanced disease stages at the time of diagnosis. This is a critical reason why the authors emphasize that \u003cstrong\u003eany suspicious or palpable breast mass that persists for 2 weeks or more during pregnancy should be investigated\u003c\/strong\u003e—even though 80% of breast lesions during pregnancy turn out to be benign.\u003c\/p\u003e\n\n\u003ch2 id=\"diagnosis-local\"\u003eDiagnosis: Examining the Breast (Local Staging)\u003c\/h2\u003e\n\n\u003cp\u003eWhen a pregnant woman has a palpable breast mass, the diagnostic workup includes clinical examination, imaging, and biopsy. The medical team will assess the disease stage according to the American Joint Committee on Cancer (AJCC) tumor, node, and metastasis (TNM) staging system.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eBreast ultrasound\u003c\/strong\u003e—including examination of the axillary (underarm) area—is the first imaging method of choice. It does not involve ionizing radiation, making it completely safe for the fetus. It also allows for immediate identification of obvious benign lesions such as cysts and galactoceles (milk-filled cysts), which require no further evaluation. When suspicious lesions are found, a biopsy can be performed using ultrasound guidance. The combined sensitivity (ability to correctly identify cancer) and specificity (ability to correctly identify non-cancer) for detecting malignancy during pregnancy are \u003cstrong\u003e80.1% and 88.4%\u003c\/strong\u003e, respectively, meaning the test correctly identifies cancer in about 4 out of 5 cancer cases and correctly rules it out in nearly 9 out of 10 non-cancer cases.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eMammography\u003c\/strong\u003e may also be performed, with either one mediolateral oblique (MLO) view or two views (MLO plus craniocaudal). When ultrasound is combined with mammography using craniocaudal and MLO views of both breasts, doctors can better assess tumor extent, multifocality (multiple tumors in one breast), or bilateral disease (cancer in both breasts). The incremental detection rate of this combined approach is comparable to that of contrast-enhanced breast MRI, finding additional cancers in \u003cstrong\u003e15.5% of cases in the ipsilateral breast\u003c\/strong\u003e (same breast as the known tumor) and \u003cstrong\u003e3.9% in the contralateral breast\u003c\/strong\u003e (opposite breast).\u003c\/p\u003e\n\n\u003cp\u003eUltrasound is also used to assess regional lymph node status. Suspicious lymph nodes can be confirmed by fine-needle aspiration or biopsy. Because of the effectiveness of ultrasound plus mammography, \u003cstrong\u003econtrast-enhanced breast MRI can generally be omitted during pregnancy\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003cp\u003eOutside of pregnancy, contrast-enhanced MRI is often used for women with BRCA gene mutations, lobular cancer, dense breast tissue, suspected multicentricity or multifocality, before neoadjuvant (pre-surgical) therapy, or when other imaging results are inconclusive. However, the use of gadolinium-based contrast agents (the \"dye\" used in MRI) is controversial during pregnancy. Although there are no known birth defect (teratogenic) effects of gadolinium-based contrast agents in humans, the U.S. Food and Drug Administration (FDA) categorizes them as \u003cstrong\u003epregnancy category C\u003c\/strong\u003e, meaning risk cannot be ruled out. Gadolinium crosses the placenta and enters fetal circulation. After excretion through the fetal urine, small amounts remaining in the amniotic fluid may break down into potentially toxic free gadolinium ions, with unclear long-term effects on the fetus. Therefore, contrast-enhanced MRI during pregnancy should only be performed when it will change clinical decision-making AND cannot be postponed until after delivery. If it is necessary, the lowest possible dose should be used.\u003c\/p\u003e\n\n\u003ch2 id=\"diagnosis-distant\"\u003eDiagnosis: Checking for Cancer Spread (Distant Staging)\u003c\/h2\u003e\n\n\u003cp\u003eJust as in non-pregnant women, further staging (checking whether cancer has spread to other parts of the body) should only be performed in high-risk early breast cancer cases. This includes situations where there are clinically positive axillary lymph nodes, large tumors (5 cm or larger), aggressive tumor biology, or clinical signs, symptoms, or laboratory values suggesting metastatic disease. In these cases, doctors consider a chest CT scan, abdominal imaging, and a bone scan.\u003c\/p\u003e\n\n\u003cp\u003ePET\/CT scans (positron emission tomography combined with computed tomography) may replace traditional imaging in some cases, but they can be less sensitive for lobular cancers and low-grade tumors.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDuring pregnancy, ultrasound and MRI are strongly preferred for staging\u003c\/strong\u003e because they do not use ionizing radiation and perform accurately. CT and PET\/CT scans can be selectively performed during pregnancy when the benefit to the mother outweighs the risk to the fetus—specifically, when results will change clinical management AND cannot be postponed until after pregnancy. When these scans are necessary, radiation doses should be kept as low as reasonably achievable, and \u003cstrong\u003ecumulative fetal radiation exposure over 100 mGy should be avoided\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003cp\u003eA newer technique called \u003cstrong\u003ewhole-body diffusion-weighted MRI\u003c\/strong\u003e can be used for staging when available. Recent studies show excellent diagnostic performance for detecting distant metastases (including in bone, liver, and peritoneum\/abdominal lining) as well as lymph node metastases in pregnant cancer patients. Studies demonstrated high inter-reader agreement, \u003cstrong\u003e90% accuracy for primary tumor detection, 98.5% to 99.5% accuracy for detecting lymph node metastases, and 90% to 100% accuracy for detecting distant metastases\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003ch2 id=\"radiation-safety\"\u003eUnderstanding Radiation Risks and Doses\u003c\/h2\u003e\n\n\u003cp\u003eFetal exposure to ionizing radiation and its related risks depend on four factors: \u003cstrong\u003egestational age, radiation dose, exposure time, and the type of nuclide used\u003c\/strong\u003e (if applicable). The influence of radiation on pregnancy varies by timing: radiation can cause fetal death in the first 2 weeks after conception, malformations up to 2 months, and decreased IQ between the 3rd and 6th month of pregnancy.\u003c\/p\u003e\n\n\u003cp\u003eRadiation effects are divided into two categories. \u003cstrong\u003eDeterministic effects\u003c\/strong\u003e—such as miscarriage, growth restriction, congenital malformations, microcephaly (abnormally small head), or impaired fetal development—occur when fetal exposure exceeds a threshold dose of \u003cstrong\u003e100 to 200 mGy\u003c\/strong\u003e. From \u003cstrong\u003e8 to 15 weeks\u003c\/strong\u003e of gestation, the fetus is most susceptible to radiation-induced mental retardation, with a reduction of \u003cstrong\u003e21 IQ points per 1,000 mGy\u003c\/strong\u003e above a threshold of about 50 mGy. From \u003cstrong\u003e16 to 25 weeks\u003c\/strong\u003e, the reduction is \u003cstrong\u003e13 IQ points per 100 mGy\u003c\/strong\u003e above the same threshold of about 50 mGy. After 25 weeks, no clear relationship has been described.\u003c\/p\u003e\n\n\u003cp\u003eReassuringly, radiation doses delivered from routine diagnostic exams are up to \u003cstrong\u003e100 times lower\u003c\/strong\u003e than these danger thresholds. However, extra caution is needed when multiple imaging studies are required, to ensure the cumulative fetal radiation dose does not inadvertently exceed safe limits.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eStochastic effects\u003c\/strong\u003e are random, unpredictable cancer-causing (oncogenic) or mutation-causing (mutagenic) effects of radiation that have no safe threshold. The carcinogenic risk appears highest during the \u003cstrong\u003efirst trimester\u003c\/strong\u003e. A fetal exposure of \u003cstrong\u003e10 to 20 mGy may increase the background risk of childhood leukemia by a factor of 1.5 to 2.0\u003c\/strong\u003e, compared to a background rate of approximately 1 in 3,000 children. Importantly, only direct exposure within the radiation field adds to fetal risk—indirect fetal exposure from scattered radiation is negligible. This means \u003cstrong\u003eabdominal shielding during radiography or CT is not necessary\u003c\/strong\u003e, and it might even increase internal scatter radiation.\u003c\/p\u003e\n\n\u003cp\u003eHere are the typical fetal radiation doses for various imaging tests, compared to the annual background radiation of \u003cstrong\u003e1.1 to 2.5 mGy\u003c\/strong\u003e that everyone receives from natural sources:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eChest X-ray: less than 0.01 mGy\u003c\/li\u003e\n  \u003cli\u003eMammography (two planes, bilateral): 0.001 to 0.01 mGy\u003c\/li\u003e\n  \u003cli\u003eCT of the head: less than 0.005 to 0.5 mGy\u003c\/li\u003e\n  \u003cli\u003eCT of the chest: less than 0.01 to 0.66 mGy\u003c\/li\u003e\n  \u003cli\u003eCT of the abdomen: 1.3 to 35 mGy\u003c\/li\u003e\n  \u003cli\u003eCT of the pelvis: 10 to 50 mGy\u003c\/li\u003e\n  \u003cli\u003eLow-dose perfusion scintigraphy: 0.1 to 0.5 mGy\u003c\/li\u003e\n  \u003cli\u003e99mTc-bone scintigraphy: 3.3 mGy\u003c\/li\u003e\n  \u003cli\u003e18F-FDG PET whole-body scintigraphy: 1.1 to 990 mGy\u003c\/li\u003e\n  \u003cli\u003e18F-FDG PET\/CT whole-body scintigraphy: 10 to 50 mGy\u003c\/li\u003e\n  \u003cli\u003e18F-FDG PET\/MRI whole-body scintigraphy: 3.334 mGy\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eNote that actual radiation doses may vary depending on the imaging device and technique used, and doses have decreased over recent decades for many imaging modalities. Fetal exposure during nuclear studies also depends on the physical and biochemical properties of the nuclide used.\u003c\/p\u003e\n\n\u003cp\u003eIn nuclear imaging, the two most commonly used tracers—\u003cstrong\u003e18F-fluorodeoxyglucose (FDG)\u003c\/strong\u003e and \u003cstrong\u003etechnetium (Tc-99m)\u003c\/strong\u003e—can be used safely in pregnant patients. Several measures can minimize fetal radiation dose during nuclear imaging:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eCareful dose calculation that accounts for physiological pregnancy changes\u003c\/li\u003e\n  \u003cli\u003eUse of a bladder catheter along with intravenous hydration to avoid accumulation of the tracer in the maternal bladder\u003c\/li\u003e\n  \u003cli\u003eAdjustment of scanning time\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eHowever, standard use of hybrid imaging with CT will increase cumulative fetal radiation exposure. As an alternative, \u003cstrong\u003ePET\/MRI is a promising new development\u003c\/strong\u003e with improved detection of distant metastases compared to PET\/CT. So far, this technique has been studied in only a small series of pregnant cancer patients, but it results in a very low fetal radiation dose (3.3 mGy).\u003c\/p\u003e\n\n\u003ch2 id=\"pathology\"\u003eTumor Types and Biological Characteristics\u003c\/h2\u003e\n\n\u003cp\u003ePathological diagnosis should be based on a core needle biopsy, classified according to the World Health Organization (WHO) classification and the AJCC TNM staging system. Breast cancer is classified into stages 0 through IV, which helps doctors determine prognosis and potential treatment approaches. Staging incorporates information about tumor biology, including tumor grade, estrogen receptor (ER) status, progesterone receptor (PR) status, human epidermal growth factor receptor 2 (HER2) status, Ki-67 (a marker of cell proliferation), and gene expression data when applicable.\u003c\/p\u003e\n\n\u003cp\u003eGene expression analysis can categorize breast cancer into four main biological subtypes:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLuminal A:\u003c\/strong\u003e ER positive, PR positive, HER2 negative, low Ki-67\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLuminal B:\u003c\/strong\u003e ER positive, PR positive, HER2 negative OR HER2 positive, high Ki-67\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHER2-enriched:\u003c\/strong\u003e ER negative, PR negative, HER2 positive\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBasal-like (triple-negative):\u003c\/strong\u003e ER negative, PR negative, HER2 negative\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003ePrBC is similar to the phenotypes most commonly found in young breast cancer patients in general. These tumors are mainly \u003cstrong\u003ehigh-grade invasive carcinomas not otherwise specified (NOS)\u003c\/strong\u003e, often with aggressive characteristics: larger tumors, a higher incidence of positive lymph nodes, and lymphovascular invasion (cancer cells in blood or lymph vessels).\u003c\/p\u003e\n\n\u003cp\u003eA large, recently published cohort derived from two registries—the INCIP registry and the German Breast Group (GBG)—compared \u003cstrong\u003e662 pregnant patients to 1,082 non-pregnant cancer patients aged up to 45 years\u003c\/strong\u003e. The findings were striking. Pregnant patients were more likely to have:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eStage II breast cancer:\u003c\/strong\u003e 60.1% vs. 56.1% (p = 0.035, statistically significant)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGrade 3 tumors:\u003c\/strong\u003e 74.0% vs. 62.2% (p \u0026lt; 0.001, highly significant)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHormone receptor-negative tumors:\u003c\/strong\u003e 48.4% vs. 34.0% (p \u0026lt; 0.001)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTriple-negative breast cancer (TNBC):\u003c\/strong\u003e 38.9% vs. 26.9% (p \u0026lt; 0.001)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eHER2 positivity was found in \u003cstrong\u003e29.2%\u003c\/strong\u003e of pregnant patients, a difference that was not statistically significant compared to non-pregnant patients. A more detailed comparison of tumor characteristics between pregnant and non-pregnant patients (with updated numbers from additional data) shows:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eMedian age: 34 years (range 22–47) in pregnant patients vs. 38 years (range 19–45) in non-pregnant patients\u003c\/li\u003e\n  \u003cli\u003eStage I: 15.4% (16.1% in updated data) vs. 30.4% (20.9%)\u003c\/li\u003e\n  \u003cli\u003eStage II: 56.9% (60.1%) vs. 46.1% (56.1%)*\u003c\/li\u003e\n  \u003cli\u003eStage III: 27.7% (23.8%) vs. 23.5% (23.0%)\u003c\/li\u003e\n  \u003cli\u003eGrade 1–2: 23.8% (26.0%) vs. 43.5% (35.8%)\u003c\/li\u003e\n  \u003cli\u003eGrade 3: 76.2% (74.0%) vs. 56% (62.2%)**\u003c\/li\u003e\n  \u003cli\u003eNon-lobular histology: 97.4% (96.6%) vs. 91% (94.6%)\u003c\/li\u003e\n  \u003cli\u003eInvasive lobular histology: 2.6% (3.1%) vs. 9% (5.4%)\u003c\/li\u003e\n  \u003cli\u003eER and\/or PR positive: 46.6% (51.6%) vs. 74.5% (66.6%)**\u003c\/li\u003e\n  \u003cli\u003eHER2 positive: 31.8% (29.2%) vs. 17% (27.2%)\u003c\/li\u003e\n  \u003cli\u003eTriple negative: 37.9% (38.9%) vs. 19.1% (26.9%)**\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e*p = 0.035; **p \u0026lt; 0.001\u003c\/p\u003e\n\n\u003cp\u003eWhen examining biological subtypes specifically, pregnant patients consistently have less luminal A disease and more basal-like\/triple-negative disease compared to non-pregnant patients:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eLuminal A: 10.8%–13.7% in pregnant vs. 24.0%–50.9% in non-pregnant\u003c\/li\u003e\n  \u003cli\u003eLuminal B: 18.2%–38.4% vs. 20.1%–21.1%\u003c\/li\u003e\n  \u003cli\u003eHER2 positive: 15.8%–29.2% vs. 8.0%–27.2%\u003c\/li\u003e\n  \u003cli\u003eBasal-like\/TNBC: 30.1%–38.9% vs. 17.4%–26.9%\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2 id=\"genetics\"\u003eGenetic Findings in Pregnancy-Associated Breast Cancer\u003c\/h2\u003e\n\n\u003cp\u003eThe most commonly mutated genes in breast cancer patients are \u003cstrong\u003eTP53\u003c\/strong\u003e and \u003cstrong\u003ePIK3CA\u003c\/strong\u003e, with no significant differences between pregnant and non-pregnant breast cancer patients. However, there are molecular differences in PrBC compared to non-pregnancy-related breast cancer, including a \u003cstrong\u003ehigher frequency of mutations in the mucin gene family\u003c\/strong\u003e and an \u003cstrong\u003eenrichment of mismatch repair deficiency mutational signature\u003c\/strong\u003e (a type of genetic instability). The mucin gene family plays a major role in glycosylation mechanisms—the process of attaching sugar molecules to proteins—and alterations in glycosylation are correlated with breast cancer development and spread.\u003c\/p\u003e\n\n\u003cp\u003eA recent systematic review summarized available data on the genomic background and gene mutation patterns of pregnancy-associated breast cancer compared to non-pregnant patients. The research found aberrant expression of several oncogenes (cancer-promoting genes) including \u003cstrong\u003eMYC, FOS, and MUC1\u003c\/strong\u003e, as well as altered expression of apoptosis regulators (genes that control programmed cell death), transcription regulators, DNA repair genes (such as \u003cstrong\u003eSig20 and BRCA1\u003c\/strong\u003e), cell proliferation genes (\u003cstrong\u003eIGF1 and MKI67\u003c\/strong\u003e), immune response genes (\u003cstrong\u003ePD1 and PDL1\u003c\/strong\u003e), and other biological processes. In contrast, the most down-regulated (suppressed) genes were tumor suppressor genes (\u003cstrong\u003eTP53 and PTEN\u003c\/strong\u003e), cell cycle regulator genes (\u003cstrong\u003eBCL2\u003c\/strong\u003e), DNA repair genes, and genes involved in protein modification and transport.\u003c\/p\u003e\n\n\u003cp\u003eResearchers hypothesize that these features may promote tumor progression during pregnancy or the postpartum period, with distinct differences between PrBC (cancer during pregnancy) and PPBC (postpartum breast cancer).\u003c\/p\u003e\n\n\u003cp\u003eGenetic counseling is especially important for women diagnosed with breast cancer during pregnancy. Women with a \u003cstrong\u003eBRCA1 germline mutation\u003c\/strong\u003e appear to have an increased risk of developing PrBC. In one study of 20 women with pregnancy-associated breast cancer using a 94-cancer gene panel, \u003cstrong\u003e7 women carried pathogenic (disease-causing) mutations in BRCA1 or CHEK2\u003c\/strong\u003e. Because of their young age at diagnosis and the clinical consequences, all women with PrBC should be referred for genetic counseling.\u003c\/p\u003e\n\n\u003ch2 id=\"treatment-overview\"\u003eTreatment Overview: Balancing Mother and Baby\u003c\/h2\u003e\n\n\u003cp\u003eThe goal of treatment during pregnancy is straightforward: \u003cstrong\u003eachieve the best possible oncological outcome for the mother\u003c\/strong\u003e while protecting the fetus. Whenever possible, physicians should follow the same standard-of-care treatment guidelines used for non-pregnant patients. Decisions about treatment are guided by patient and tumor characteristics, cancer stage, gestational age, and the wishes of the patient and her partner regarding continuation of the pregnancy.\u003c\/p\u003e\n\n\u003cp\u003eIt is essential to establish early on whether treatment is curative or palliative in intent, as this affects all subsequent decisions, including those about continuing the pregnancy. A multidisciplinary team should assess and weigh the medical (obstetrical), oncological, radiotherapeutic, pediatric, molecular\/genetic, ethical, and psychological issues. The patient and her partner need careful counseling about treatment options, maternal and fetal risks, and decisions concerning continuation or termination of the pregnancy.\u003c\/p\u003e\n\n\u003cp\u003eA crucial finding from the research is that \u003cstrong\u003etermination of pregnancy has NOT been shown to improve maternal outcomes\u003c\/strong\u003e for breast cancer. Therefore, premature delivery or unnecessary delay in diagnosis or treatment—just to start treatment after birth—should be avoided. Prematurity can often be minimized by starting cancer treatment during pregnancy.\u003c\/p\u003e\n\n\u003cp\u003eHere is how each major treatment modality fits into pregnancy:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSurgery:\u003c\/strong\u003e Possible during all trimesters\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRadiotherapy:\u003c\/strong\u003e Possible during the first half of pregnancy\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eChemotherapy:\u003c\/strong\u003e Can be safely administered starting from \u003cstrong\u003e12 weeks of gestational age\u003c\/strong\u003e (after the first trimester, when the baby's organs are formed)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEndocrine therapy\u003c\/strong\u003e (hormone-blocking treatments like tamoxifen or aromatase inhibitors): \u003cstrong\u003eContraindicated throughout the entire pregnancy\u003c\/strong\u003e\n\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHER2-targeted therapy\u003c\/strong\u003e (such as trastuzumab): \u003cstrong\u003eContraindicated throughout the entire pregnancy\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eImportantly, fetal growth should be monitored regularly during cancer treatment, and long-term follow-up of the children is encouraged in dedicated centers.\u003c\/p\u003e\n\n\u003ch2 id=\"surgery\"\u003eSurgery During Pregnancy\u003c\/h2\u003e\n\n\u003cp\u003eBreast cancer surgery can be performed safely during any stage of pregnancy. Currently used anesthetics at standard concentrations are not known to have any birth defect (teratogenic) effects. The passage of anesthetic medication through the placenta depends on its lipophilicity (fat solubility), degree of ionization, molecular mass, and protein binding. The timing of surgery should be based on patient and tumor characteristics, gestational age, and patient preferences. Elective (non-urgent) surgery should be postponed until after delivery.\u003c\/p\u003e\n\n\u003cp\u003eIn general, risks of surgery during pregnancy include preterm delivery, miscarriage, and fetal distress. However, in non-abdominal surgery (which breast surgery is), these risks are small. Adequate maternal care during the perioperative period is the most important factor for fetal well-being. After 20 weeks of gestation, the patient should be positioned in a \u003cstrong\u003eleft lateral tilt\u003c\/strong\u003e to ensure optimal blood flow through the vena cava (the large vein returning blood to the heart).\u003c\/p\u003e\n\n\u003cp\u003eCertain conditions must be actively prevented because they can harm fetal health and development: hypoxia (low oxygen), hypotension (low blood pressure), hypoglycemia (low blood sugar), fever, pain, infections, and thrombosis (blood clots). Placental perfusion (blood flow) is determined primarily by maternal blood pressure and lacks autoregulation—meaning that if the mother's blood pressure drops due to hemorrhage or low blood volume, placental blood flow decreases and the fetus can become缺氧 (oxygen-deprived).\u003c\/p\u003e\n\n\u003cp\u003eMonitoring of fetal heart rate (FHR) by cardiotocography (CTG) during surgery is debatable but can be useful to detect fetal distress, depending on gestational age and potential viability (whether the baby could survive if delivered early). If fetal monitoring is used, it is recommended to perform surgery at an institution with neonatal and pediatric services, and to have an obstetric care provider readily available. Obstetricians should be aware that fetal heart rate patterns will be influenced by anesthesia and surgery. Nonetheless, \u003cstrong\u003eCTG before and after a procedure is a minimum requirement\u003c\/strong\u003e. If there are signs of fetal distress, staff should consider repositioning the patient, and providing fluid replacement and oxygen.\u003c\/p\u003e\n\n\u003cp\u003eOther perioperative measures include pain medication (since excessive pain may trigger preterm labor) and appropriate \u003cstrong\u003ethromboprophylaxis with low molecular weight heparin (LMWH)\u003c\/strong\u003e to reduce the risk of venous thromboembolic events (blood clots in veins).\u003c\/p\u003e\n\n\u003cp\u003eRegarding the type of breast surgery, the choice during pregnancy should follow the same guidelines as for non-pregnant women, favoring breast-conserving therapy when feasible. If immediate breast reconstruction is considered, \u003cstrong\u003eprosthetic implants are possible\u003c\/strong\u003e, but \u003cstrong\u003eautologous reconstruction\u003c\/strong\u003e (using the patient's own tissue) should be \u003cstrong\u003edelayed until after delivery\u003c\/strong\u003e, taking physiological changes into account. Importantly, the need for radiotherapy after breast-conserving surgery should \u003cstrong\u003enot\u003c\/strong\u003e be used as an argument to favor mastectomy, because radiotherapy can safely start after delivery.\u003c\/p\u003e\n\n\u003cp\u003eThe following medications can be used safely during and after surgery:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAnesthetics:\u003c\/strong\u003e Desflurane, Propofol\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePain medications:\u003c\/strong\u003e Opiates including sufentanil (maximum 30 mg) and morphine; Lidocaine; Ketamine\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAnti-nausea medications:\u003c\/strong\u003e Ondansetron, metoclopramide, granisetron\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSteroids:\u003c\/strong\u003e Hydrocortisone, methylprednisolone, prednisolone, dexamethasone (note: methylprednisolone, hydrocortisone, and prednisolone are preferred because they are metabolized in the placenta, leading to lower concentrations in the fetus)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eStomach acid reducers:\u003c\/strong\u003e Proton pump inhibitors\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eDiscouraged medications include:\u003c\/strong\u003e NSAIDs (non-steroidal anti-inflammatory drugs, except when used specifically as anti-tocolytic agents to stop preterm labor) and Metamizole (an analgesic not recommended in pregnancy).\u003c\/p\u003e\n\n\u003ch2 id=\"sentinel-node\"\u003eSentinel Lymph Node Biopsy: Checking for Lymph Node Spread\u003c\/h2\u003e\n\n\u003cp\u003eSentinel lymph node staging—the procedure used to determine whether cancer has spread to the first (sentinel) lymph node draining the breast—can be performed safely during pregnancy. In a study of premenopausal non-pregnant patients who underwent peritumoral injection of \u003cstrong\u003e12 MBq of technetium-99m (99m-Tc)\u003c\/strong\u003e, the radioactive tracer was found only at the injection site and in the sentinel node, with none traceable in the abdomen. This confirmed that the tracer does not reach the fetus in measurable amounts.\u003c\/p\u003e\n\n\u003cp\u003eSafety was also confirmed in another study involving \u003cstrong\u003e25 pregnant patients\u003c\/strong\u003e who underwent the procedure using 99m-Tc and\/or methylene blue dye. However, if a sentinel lymph node procedure is performed, \u003cstrong\u003eblue dye (Patent Blue®) should be avoided\u003c\/strong\u003e, as it carries a small risk of a severe allergic reaction (anaphylaxis) in the mother, which could subsequently cause fetal distress.\u003c\/p\u003e\n\n\u003ch2 id=\"clinical-implications\"\u003eClinical Implications: What This Means for Patients\u003c\/h2\u003e\n\n\u003cp\u003eFor women diagnosed with breast cancer during pregnancy, these findings translate into several practical and important messages:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eYou can be treated during pregnancy.\u003c\/strong\u003e Modern cancer treatment, including surgery and chemotherapy after the first trimester, is safe for both mother and baby when performed at a specialized center.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDelaying treatment is rarely the right choice.\u003c\/strong\u003e Termination of pregnancy has not been shown to improve outcomes, and delaying cancer treatment to avoid treatment during pregnancy can worsen the mother's prognosis while also increasing the risks of prematurity from early delivery.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBeing diagnosed during pregnancy does not automatically mean your tumor is different.\u003c\/strong\u003e While PrBC is statistically more likely to be triple-negative or higher grade, the overall approach is to treat it according to standard guidelines based on your specific tumor's biology.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSpecialized multidisciplinary care matters.\u003c\/strong\u003e Treatment decisions involve balancing complex oncological, obstetrical, and fetal considerations, so having a team experienced in cancer in pregnancy is essential.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSome treatments are off-limits during pregnancy.\u003c\/strong\u003e Endocrine therapy and HER2-targeted therapy (such as trastuzumab) are contraindicated while pregnant, and these treatments are typically deferred until after delivery.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFetal monitoring is standard.\u003c\/strong\u003e Growth ultrasounds and monitoring during surgery help ensure the baby is developing well and identify any complications early.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLong-term follow-up of children is recommended.\u003c\/strong\u003e Children exposed to cancer treatment in the womb should be followed in dedicated centers to track their development over time.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2 id=\"limitations\"\u003eLimitations of This Research\u003c\/h2\u003e\n\n\u003cp\u003eWhile this review provides a comprehensive summary of current evidence, several limitations should be acknowledged. First, much of the data on breast cancer during pregnancy comes from observational cohort studies rather than randomized controlled trials, which are difficult to conduct in pregnant patients for ethical and practical reasons. Second, the relatively small number of patients in some studies limits the statistical power and generalizability of findings. Third, the research on long-term outcomes for children exposed to cancer treatment during pregnancy is still evolving, with many questions remaining about subtle developmental effects that may only appear later in life. Fourth, the molecular and genetic findings, while promising, come from small studies and have not yet been fully validated in larger, prospective cohorts. Finally, the authors note that the incidence of breast cancer during pregnancy is rising due to delayed childbearing, meaning that ongoing research is needed to keep pace with changing demographics.\u003c\/p\u003e\n\n\u003ch2 id=\"recommendations\"\u003eRecommendations for Patients\u003c\/h2\u003e\n\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReport any breast changes promptly.\u003c\/strong\u003e If you notice a lump, nipple discharge, or other breast change that persists for 2 weeks or more during pregnancy, ask your doctor for a clinical breast examination and appropriate imaging (typically ultrasound). Do not assume it is just a normal pregnancy change.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSeek care at a specialized, multidisciplinary center.\u003c\/strong\u003e Look for a hospital or cancer center with experience treating cancer during pregnancy, including expertise in obstetrics, oncology, surgery, radiology, and pediatrics. Dedicated tumor boards for cancer in pregnancy can provide individualized recommendations.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAsk about genetic counseling.\u003c\/strong\u003e Because breast cancer at a young age can be associated with inherited mutations such as BRCA1 and CHEK2, genetic counseling and testing should be part of your care.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDiscuss the full range of treatment options\u003c\/strong\u003e with your care team, including the timing of surgery\n\n\u003c!-- ddn:faq:start --\u003e\n\u003ch2 id=\"ddn-faq\"\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003ch3\u003eIs it safe to receive breast cancer treatment while I am pregnant?\u003c\/h3\u003e\n\u003cp\u003eYes, in many cases. The research shows that surgery can be done in any trimester, and chemotherapy can be safely given after the 12th week of pregnancy. However, some treatments like endocrine therapy and HER2-targeted therapy are not used during pregnancy. A specialized multidisciplinary team should plan your treatment carefully.\u003c\/p\u003e\n\u003ch3\u003eWill cancer treatment harm my baby?\u003c\/h3\u003e\n\u003cp\u003eWhen treatment is planned by a specialized team, most women can continue their pregnancy. Chemotherapy after the first trimester is generally safe, but it has been linked in one large study to a higher chance of the baby being small for gestational age or needing neonatal intensive care. Fetal growth is monitored regularly during cancer treatment.\u003c\/p\u003e\n\u003ch3\u003eShould I consider terminating my pregnancy to improve my cancer outcome?\u003c\/h3\u003e\n\u003cp\u003eNo. Termination of pregnancy has not been shown to improve maternal outcomes for breast cancer. Delaying cancer treatment or delivering early to start treatment after birth can be harmful. Starting cancer treatment during pregnancy may actually reduce the risks of prematurity by allowing the pregnancy to continue closer to full term.\u003c\/p\u003e\n\u003ch3\u003eIs breast cancer during pregnancy more aggressive or different from other breast cancer?\u003c\/h3\u003e\n\u003cp\u003eCompared to non-pregnant younger patients, pregnant patients in two large registries were more likely to have higher-grade tumors, hormone receptor-negative tumors, and triple-negative breast cancer. But the approach is to treat according to your specific tumor's biology using standard guidelines, just as for non-pregnant patients.\u003c\/p\u003e\n\u003ch3\u003eWhat tests can I safely have to diagnose and stage breast cancer during pregnancy?\u003c\/h3\u003e\n\u003cp\u003eBreast ultrasound is the first imaging choice and is completely safe. Mammography can also be used with abdominal shielding not being necessary. Contrast-enhanced MRI is generally avoided unless it will change your care. For staging, ultrasound and MRI are strongly preferred over CT or PET\/CT scans, which are used only if necessary.\u003c\/p\u003e\n\u003ch3\u003eCan I have breast surgery or a sentinel lymph node biopsy while pregnant?\u003c\/h3\u003e\n\u003cp\u003eYes. Breast cancer surgery can be performed safely during any trimester. Care is taken to position you appropriately after 20 weeks and to prevent problems like low blood pressure or low oxygen. Sentinel lymph node biopsy with a radioactive tracer is safe, but blue dye should be avoided due to a small risk of allergic reaction.\u003c\/p\u003e\n\u003ch3\u003eWhat is the chance that my baby will be born alive and healthy after cancer treatment during pregnancy?\u003c\/h3\u003e\n\u003cp\u003eIn a large international study of 1,170 patients, 88% of singleton pregnancies resulted in a live birth, though 48% were preterm. Preterm births and NICU admissions were more common with chemotherapy exposure before birth. Careful monitoring and specialized care are essential to help protect the baby.\u003c\/p\u003e\n\u003ch3\u003eShould I get a second opinion if my doctor recommends delaying breast cancer treatment until after I give birth?\u003c\/h3\u003e\n\u003cp\u003eYes, a second opinion is reasonable when treatment timing is uncertain. Breast cancer during pregnancy can often be treated safely with surgery and chemotherapy after the first trimester. Starting treatment during pregnancy rather than delaying delivery can lower prematurity risks, while postponing care may worsen the mother's prognosis. A multidisciplinary specialist team should guide decisions, and a second opinion can confirm whether your proposed plan follows standard pregnancy-specific protocols. Diagnostic Detectives Network provides independent expert second opinions.\u003c\/p\u003e\n\u003c!-- ddn:faq:end --\u003e\n\u003c\/li\u003e\n\u003c\/ol\u003e","brand":"DiagnosticDetectives.Com","offers":[{"title":"Default Title","offer_id":47545194741916,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true}],"url":"https:\/\/diagnosticdetectives.com\/de\/products\/breast-cancer-during-pregnancy-a-comprehensive-guide-to-diagnosis-treatment-and-safety-for-mother-and-baby","provider":"DiagnosticDetectives.Com","version":"1.0","type":"link"}