May 21, 2010
Dear Mayo Clinic:
My 32-year-old son visited his doctor because he was having some rectal bleeding. His doctor performed a flexible sigmoidoscopy and discovered a polyp, which she was not able to remove, but recommended he have a colonoscopy soon. She asked about siblings and family history and said his 37-year-old sister should be checked. How common is it for someone to have polyps at this age?
Colon polyps before age 50 are uncommon. Your son's condition should be explored further, as his doctor recommends. Family history plays a role in colon cancer. But whether his sister needs a colon exam at this time depends on the type of polyp that your son has, as well as other possible risk factors.
A colon polyp is a small clump of cells that forms on the lining of the colon. Most colon polyps are harmless, but some can become cancerous. The majority of people with colon polyps are 50 or older. The risk for polyps starts increasing around age 40. Additional risk factors include being overweight, smoking, eating a high-fat, low-fiber diet, and having a personal or family history of colon polyps or colon cancer.
The polyp your son has may be one of two main types. The first type of polyp is called an adenoma. About two-thirds of polyps fall into this category. Although only a small percentage of these polyps become cancerous, nearly all malignant polyps are adenomas. The second type is a hyperplastic polyp. These polyps are usually tiny and very rarely do they become cancerous. Juvenile and hamartomatous polyps are two other extremely rare types of polyps.
Colonoscopy is an appropriate next step in your son's situation. Unlike sigmoidoscopy — which uses a shorter scope that can examine only about one-third to one-half of the colon — colonoscopy uses a scope that can reach the entire colon. The longer scope will allow the doctor better access to the polyp for removal, as well as permit an exam of all the colon lining to see if other polyps have formed. After the colonoscopy, a pathologist will examine the polyp tissue under a microscope to determine its type and whether it's cancerous.
If your son's polyp is tiny and hyperplastic, it's not necessary for your daughter to have a colon exam at this time because of the very low rate of cancer developing from that type of polyp. However, hyperplastic polyps that are 1 centimeter or larger may indicate a risk for colon cancer and the need for colon cancer screening.
If it's a larger hyperplastic polyp or an adenoma-type polyp, your daughter should talk to her doctor about colon cancer screening. People who have a first-degree relative (parent, sibling or child) with colon polyps or colon cancer are more likely to develop polyps or cancer themselves.
If your daughter needs to be screened, it would be helpful for her (and your son) to know if there's a family history of any other type of cancer — particularly endometrial cancer — as that could be associated with increased chance of developing colon cancer. The doctor will want to know the kind of cancer, the type of relative (aunt or uncle, grandparent, niece or nephew, for example), and the age at which they developed cancer.
Colon screening typically begins at age 50 and continues every five to ten years depending on the presence of polyps and the type of screening. For people who have a first-degree relative with colon cancer or polyps before age 60, screening often begins at 40.
If your son's polyp is an adenoma and is not cancerous, he should have regular follow-up care to monitor for additional polyps and other possible signs of colon cancer. Screening tests play a key role in detecting polyps before they become cancerous and can also find colon cancer in its early stages. When early-stage colon cancers are found and removed promptly, the long-term survival rate is often very high.
— Lisa Boardman, M.D., Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minn.