Colon Cancer Symptoms and Early Detection Strategies

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• Why Colon Cancer Often Has No Early Symptoms
• 3 Hereditary Colon Cancer Warning Signs
• Proximal vs Distal Colon Cancer Symptoms
• When Colon Cancer Causes Weight Loss and Pain
• Optimal Colonoscopy Intervals for Prevention
• How Annual Screening Stops Lynch Syndrome Cancers
• Full Transcript

Why Colon Cancer Often Has No Early Symptoms

Dr. C. Richard Boland, MD emphasizes that colorectal cancer typically causes no symptoms until advanced stages. Distal colon cancers near the sigmoid colon may eventually cause bowel obstruction, while many patients only develop subtle anemia from slow bleeding. "A big problem with colon cancer is that it does not cause symptoms until it's quite late," explains Dr. Boland. This silent progression makes screening critical for early detection before symptoms appear.

3 Hereditary Colon Cancer Warning Signs

Dr. Boland identifies three key indicators of hereditary colon cancer syndromes like Lynch syndrome: diagnosis before age 50 (early onset), multiple primary colon tumors in one patient, and strong family history of colorectal cancer. "These would be three major ways of knowing about hereditary colon cancer," notes Dr. C. Richard Boland, MD. Patients with these red flags require genetic testing and more frequent surveillance.

Proximal vs Distal Colon Cancer Symptoms

Tumor location significantly affects symptom presentation, according to Dr. Boland. Two-thirds of Lynch syndrome cancers occur in the proximal colon (cecum, ascending, transverse), which rarely obstructs due to its larger diameter but often causes bleeding leading to anemia. Distal colon cancers near the rectum more commonly cause obstruction. Dr. C. Richard Boland, MD observes that 30% of proximal colon tumors display microsatellite instability regardless of hereditary status.

When Colon Cancer Causes Weight Loss and Pain

Microsatellite unstable tumors trigger unique inflammatory symptoms through immune system activation. "Patients get symptoms of inflammation: pain or a lot of weight loss," explains Dr. Boland. This results from cytokine production during the biological battle between tumor cells and infiltrating lymphocytes. However, Dr. C. Richard Boland, MD cautions that abdominal pain represents late-stage disease, underscoring the need for screening before symptoms develop.

Optimal Colonoscopy Intervals for Prevention

For average-risk patients, Dr. Boland recommends colonoscopy every 10 years due to slow adenoma-to-carcinoma progression (typically 10-15 years). "Polyp formers" may need screening every 5 years. Dr. C. Richard Boland, MD stresses that more frequent exams aren't necessary for sporadic cases: "Patients don't really have to do colonoscopies more than every five years." This contrasts sharply with hereditary cancer syndromes requiring annual surveillance.

How Annual Screening Stops Lynch Syndrome Cancers

Dr. C. Boland, MD, highlights the dramatic success of annual colonoscopy for Lynch syndrome patients, where polyp-to-cancer progression accelerates to 1-3 years. "It dramatically alters the natural history," he states, noting many mutation carriers reach their 60s-70s cancer-free through regular polyp removal. Dr. C. Richard Boland, MD concludes: "We can prevent colon cancer, not just find it early." This preventive approach represents the gold standard for hereditary cancer syndromes.

Full Transcript

Dr. Anton Titov, MD: What are typical symptoms of colorectal cancer? Symptoms of early stage colon cancer and late stage colorectal cancer symptoms can be different. How do people discover they have Lynch syndrome?

Dr. C. Boland, MD: A big problem with colon cancer is that it does not cause symptoms until it's quite late in its course. A person who has a distal colon cancer, for example, in the sigmoid colon, might experience a bowel obstruction. But other people with colon cancer might just slowly bleed and have anemia. Even more often, an early stage colon cancer has no symptoms at all.

People who have colon cancer don't know they have it unless colon cancer is advanced in stage. In cases of hereditary forms of colon cancer, people might be on the alert that they could be in a familial colorectal cancer situation for three reasons: if they had an early onset colon cancer, if they had multiple colon cancers in their lifetime, or if there is a positive family history of colon cancer.

Those would be three major ways of knowing about hereditary colon cancer: positive family history, early onset, and multiple tumors in one person.

Dr. Anton Titov, MD: Is there a difference in the symptoms and presentation between the colon cancers located in the more proximal parts of colon versus the more distal colon cancers?

Dr. C. Boland, MD: That's a good point! Two thirds of Lynch syndrome colon cancers are in the proximal colon. The proximal colon is bigger in diameter and very unlikely to become obstructed. But the proximal colon is likely to bleed.

Oftentimes, a person with a cancer in the cecum, ascending colon, or transverse colon will have bleeding. These patients will present with anemia. About 30% of tumors in the proximal colon, not only hereditary colon cancers but also non-hereditary tumors, have a phenotype called microsatellite instability.

Microsatellite instability generates a number of immunogenic peptides, which then brings a lot of inflammatory cells into the tumor. So patients get symptoms of inflammation: pain or a lot of weight loss, probably caused by the cytokines that are made by all that immune activity. There is a huge biological battle between the tumor and the infiltrating lymphocytes.

Dr. Anton Titov, MD: But, as you mentioned previously, having abdominal pain is quite a late symptom of colorectal cancer.

Dr. C. Boland, MD: Yes, that's true. Our goal is to find ways to diagnose colon cancer before there's pain as a symptom. That's where the surveillance and screening of precancerous and early cancerous lesions is very important.

For most people in North America and Europe, about 95% of colorectal cancers are sporadic. We sometimes find that a person is a "polyp former." They get polyps that might even occur in a family. Polyp formation might be caused by shared family dietary or other environmental exposures much more so than by genes.

If we find someone at high risk for colon cancer due to increased polyp formation, we might start a colonoscopy regimen. But even a very aggressive colonoscopy regimen would be doing another colonoscopy every five years, because of the known slow progression from adenoma to carcinoma.

Patients don't really have to do colonoscopies more than every five years. In some instances, the risks of colon cancer are only moderate, so colonoscopy every 10 years would be good enough.

But in cases of Lynch syndrome, there is a very accelerated adenoma to carcinoma progression. So colonoscopies have to be done every year. When we do colonoscopies every year, it dramatically alters the natural history of Lynch syndrome and prevents people from getting cancers to begin with.

That is a wonderful result. We are able to prevent colon cancer, not just find the cancer early and do the surgical operation. We can remove polyps during screening colonoscopy and prevent colon cancer.

We have people who know they have Lynch syndrome, we found the germline mutation, but they get their colonoscopies regularly. They get to be in their 60s and 70s, and they have never had colon cancer.