Leading expert in CT colonography, Dr. Perry Pickhardt, MD, explains how virtual colonoscopy targets advanced neoplasia. Advanced neoplasia is the key precancerous lesion that progresses to colon cancer. CT colonography detects advanced neoplasia as effectively as regular colonoscopy. Virtual colonoscopy is more cost-effective and has fewer complications. Dr. Pickhardt details the clinical advantages of this screening method.
Plus de Colorectal Cancer
Plus de Diagnostic Detectives Network
Advanced Neoplasia Detection with Virtual Colonoscopy for Colorectal Cancer Prevention
Jump To Section
- What is Advanced Neoplasia?
- Virtual vs. Regular Colonoscopy for Detection
- Clinical Effectiveness and Advantages
- Cost-Effectiveness and Safety Profile
- Importance of Timely Detection
- Limitations of Other Screening Tests
- Full Transcript
What is Advanced Neoplasia?
Advanced neoplasia is the most important target for colorectal cancer screening. Dr. Perry Pickhardt, MD, defines it as a combination of advanced adenomas and invasive cancer. Advanced adenomas are precancerous polyps measuring 1 centimeter or larger. They may have a prominent villous component or contain high-grade dysplasia. These lesions have a high likelihood of progressing to invasive colon cancer.
Virtual vs. Regular Colonoscopy for Detection
CT colonography, or virtual colonoscopy, is a highly effective method for detecting advanced neoplasia. Dr. Perry Pickhardt, MD, references a landmark 2007 New England Journal of Medicine study. This head-to-head comparison showed the advanced adenoma detection rate for virtual colonoscopy was as good as, or slightly better than, regular colonoscopy. Crucially, CT colonography detected more colon cancers even though far fewer polyps were removed overall.
Clinical Effectiveness and Advantages
Virtual colonoscopy offers significant clinical advantages beyond evaluating the colon. Dr. Perry Pickhardt, MD, explains that a standard colonoscopy only examines the large bowel. In contrast, a CT colonography scan provides a view of the entire abdomen and pelvis. This allows for the incidental detection of cancers in other organs. This extracolonic finding is a major benefit that enhances the overall value of the screening test for patients.
Cost-Effectiveness and Safety Profile
The safety and cost-effectiveness of virtual colonoscopy are superior to optical colonoscopy. Dr. Perry Pickhardt, MD, highlights a critical finding from their study. There were zero complications in the virtual colonoscopy arm, which included over 3,000 patients. The regular colonoscopy group experienced seven bowel perforations. By focusing only on removing clinically significant advanced neoplasia and leaving tiny polyps, CT colonography reduces unnecessary procedures, costs, and patient risk.
Importance of Timely Detection
Finding advanced neoplasia in time is the central goal of all effective cancer screening. Dr. Anton Titov, MD, and Dr. Perry Pickhardt, MD, discuss the progression timeline. An advanced adenoma may be 5 to 10 years away from becoming an invasive colon cancer. These lesions are 20 times more common than invasive cancer at the time of screening. Detecting and removing them is the primary method of preventing cancer from developing in the first place.
Limitations of Other Screening Tests
Stool-based tests have a major limitation in colorectal cancer prevention. Dr. Perry Pickhardt, MD, notes that tests like fecal occult blood testing (FOBT) and stool DNA testing can detect many cancers. However, they often fail to detect the large, precancerous polyps known as advanced neoplasia. A patient could have a negative stool test but still harbor a dangerous polyp that will become cancer in a few years. This failure to find the precancerous target is a critical shortcoming.
Full Transcript
Dr. Anton Titov, MD: What is the best method to find precancerous lesions in the large bowel? How does virtual colonoscopy compare with regular colonoscopy? A leading virtual colonoscopy screening expert discusses CT colonography.
Advanced neoplasia is an important type of polyp in the large bowel. Advanced neoplasia eventually progresses to colon cancer. What is advanced neoplasia? How well can virtual colonoscopy detect advanced neoplasia? How can CT colonography prevent invasive colon cancer?
Dr. Perry Pickhardt, MD: This is a very important concept. Advanced neoplasia includes advanced adenomas. They are defined as any large precancerous adenoma that measures one centimeter or larger. Advanced adenoma contains a prominent villous component. It is a tubular villous adenoma or a villous adenoma. Adenoma may have high-grade dysplasia. This is the least common of colon adenomas that we encounter.
You may combine advanced adenomas with invasive cancer. The combined term for those is advanced neoplasia. Advanced neoplasia is clearly the target for screening and prevention of colorectal cancer.
Dr. Anton Titov, MD: With CT colonography and colonoscopy, the goal is to find these important lesions. We have to prevent cancers and detect cancers.
Dr. Perry Pickhardt, MD: We can leave the vast majority of the tiny polyps, or diminutive lesions, alone. Because over 50% of the population will have these tiny polyps that never progress to cancer. Removing them only increases costs and adds complications. By really targeting the sweet spot helps.
Advanced neoplasia detection by CT colonography is more cost effective and more clinically effective than regular colonoscopy. We have shown this in a New England Journal of Medicine article published in 2007. We showed head to head that the advanced adenoma detection rate was as good or slightly better for virtual colonoscopy.
More colon cancers are detected by CT colonography. Even though many fewer polyps were removed. There were no complications in the virtual colonoscopy arm of over 3,000 patients. There were seven perforations of large bowel in the regular colonoscopy group.
We also detected a number of cancers outside of the colon with CT colonography. With regular colonoscopy you only evaluate the colon. You get no other advantage in terms of detection of cancer in other organs. Virtual colonoscopy can detect cancers within the abdomen and pelvis.
By doing virtual colonoscopy, you are able to find just as many lesions overall. You are also finding clinically relevant lesions. This is advanced neoplasia. They will progress to invasive colon cancer. This is why they must be found and removed in time.
Dr. Anton Titov, MD: Yes, that is correct. These advanced adenomas may be five or even ten years away from becoming invasive colon cancer. But advanced neoplasia lesion may become large. Then we feel the likelihood that they will eventually progress to colon cancer is high enough. We want to detect all advanced neoplasia lesions in the colon. These are 20 times more common than invasive colon cancer at screening.
But advanced neoplasia lesions can be missed. Even though the patient feels that they are done with colon cancer screening.
Dr. Perry Pickhardt, MD: Then we haven't done our job properly. Tests like fecal occult blood testing and stool DNA testing do not help. Unfortunately, they can detect many colon cancers, sometimes the majority.
Dr. Anton Titov, MD: But they fail to detect these precancerous large polyps that may become cancer in the next five years or so.
Virtual colonoscopy cancer screening can detect advanced colorectal neoplasia. This is the most common precancerous lesion. Advanced neoplasia transforms into invasive colon cancer. Colorectal cancer screening has the goal to detect advanced neoplasia in all patients.
Advanced neoplasia includes both advanced adenomas. Advanced adenomas are any large precancerous adenoma that measures one centimeter or larger. Virtual colonoscopy targets the sweet spot, advanced neoplasia. CT colonography is more cost effective and more clinically effective than regular colonoscopy. Advanced neoplasia lesions are 20 times more common than invasive colon cancer at screening.