A month ago, I asked you to pretend to do colonoscopy.
A half-inch polyp turned out to be an adenoma. This was judged to be a true neoplasm, a growth that replicated and enlarged. They can be benign and push things aside, or malignant.
This showed no sign of cancer. It’s an adenoma, not an adenocarcinoma. One-centimeter polyps have a modest chance of containing a cancer. By the time it grows to two centimeters the risk rises to about 50 percent. If we find nothing else in this patient’s colon, we will consider following him more closely than average, but not with a sense of urgency.
It appears to take about five to 10 years for a benign lesion to progress to malignancy.
OK, we’re back inside the colon — at least our scope is in to the hilt. I urge you to look in every recess on the way out, distending the colon with air to minimize the risk of missing another lesion.
Having found one neoplasm, the odds of finding another are increased. The second one is flat, aka sessile, an inch across and bleeds to the touch. You snip a tiny piece that shows tumor taking root in the muscular wall. It’s malignant.
The patient’s outlook is still good. Describing treatment options could fill a book. Accept that things are getting better in colon cancer management. The development of endoscopic surgery and advances in chemotherapy have offered major advances.
Even patients with metastases to the liver are frequently living for years on new regimens. The costs are huge, but the options have clearly improved over the past decade or two.
The basic approach to cancer treatment over the years favors surgery for anything that can be excised completely. Radiation can reduce some cancers to render them operable and it is used after surgery to reduce the chance of local recurrence.
Chemotherapy also shrinks some tumors and may eliminate microscopic spread. Our tools now include agents that shut down the blood supply to metastases. If there is interest in specific treatments, I can look into them here or on my blog, Cancer Calliope (larrymulkerin.com).
For most of you who read this, I think prevention is a more useful topic.
Understanding what created your patient’s benign polyp and what probably happened to turn a second one into a cancer may tell us whether we can do anything to keep it from happening to us.
Benign polyps are the result of overgrowth of cells that don’t invade. The colon polyp gives us a way to look at processes that may cause other kinds of cancer, but we have to be careful in making assumptions.
Some cancers may start out as bad actors and others may be very indolent or even mislabeled as malignancies. Those facts can make us overconfident about screening.
Recall that colonoscopy can reduce colon death rates by more than half. That’s not bad and probably better than other screening, but we’re still learning. Most polyps seem to result from damage to the gene APC, which restricts growth by making enzymes that can break down excess or abnormal cells.
A small percentage of polyps result from an inherited abnormality. Some may happen as a random error in cell reproduction. The ones that interest me are the ones we can do something about.
Ask in a health food store and you might be told to load up on antioxidants that block chemical damage to DNA. A nutritionist isn’t a well-defined term, but one of those might tell you to ingest lots of fiber and reduce contact time between bad chemicals in food and the bowel wall.
Your family physician may suggest aspirin. In each case, I hope you ask what evidence supports the claim. What is the chance that intervention may do more harm than good? What is the most prudent choice in the presence of uncertainty?
Can we change our diet, medications or lifestyle to prevent polyps from occurring in the first place? I’ll open the next time with the aspirin story and move from there to antioxidants.
Dr. Larry Mulkerin is a retired clinical professor. He can be reached at firstname.lastname@example.org.