When it comes to family history, it’s important to know what types of cancer are present in your family, who has been affected, and how old they were when they were diagnosed. (This downloadable family tree can help you keep a record.)
In terms of colon health, it can be helpful to keep track of how many colon polyps and what type of polyps you’ve had. These key pieces of information can help a licensed genetic counselor assess your risk for a hereditary cancer syndrome. According to the American Cancer Society, it is estimated that 5-10% of all cancer is hereditary, meaning that some people are born genetically more likely to develop a certain type(s) of cancer.
Up to 1-3 percent of all colorectal cancer is caused by one single genetic condition: Lynch syndrome. Lynch syndrome is a condition that can present increased risks for the development of colorectal cancer, gastric cancer, endometrial cancer, ovarian cancer, and sometimes other cancers. Of all hereditary cancer syndromes relevant to colorectal cancer, Lynch syndrome is the most well-known, but is not the only hereditary cancer syndrome that predisposes individuals to developing colorectal cancer. (Watch as TV anchor Jerry Anderson undergoes genetic testing to see if he has Lynch syndrome.)
Some other lesser known hereditary cancer syndromes are Familial Adenomatous Polyposis (FAP) syndrome, Attenuated Familial Adenomatous Polyposis (AFAP) syndrome, and MUTYH-Associated Polyposis (MAP) syndrome.
Familial Adenomatous Polyposis: FAP is a condition that causes an individual to develop hundreds of colon polyps. When untreated, the colorectal cancer risk with FAP is nearly 100 percent, and risk of other cancers is there but less frequent. If one of your parents have FAP, you have a 50/50 chance of having it.
Attenuated Familial Adenomatous Polyposis: AFAP is a less severe version of FAP. People typically develop 10-100 adenomatous polyps in their lifetime, typically later in life. About three in 100,000 people have either FAP or AFAP. In the past, it was estimated that 0.5 percent of all colorectal cancer was due to FAP/AFAP, however this number may be decreasing due to early detection of colon polyps. If one of your parents has AFAP, you have a 50/50 chance of having it.
MUTYH-Associated Polyposis: MAP is similar to FAP and AFAP in that it can cause colorectal polyps, but it is inherited differently. With MAP, both of your parents must to be carriers and pass both of their affected MUTYH genes on to you for you to be affected. Many people with MAP don’t present with colon polyps until later in life and people with MAP can have anywhere from 10 to a few hundred adenomatous polyps. Other types of polyps and even polyps in the duodenum (first section of the small intestine) may develop.
Early and increased screening frequency, and sometimes preventive surgeries have the power to lower the risk of colorectal cancer in individuals who are affected by these conditions. Individuals who have Lynch syndrome, AFAP or MAP are recommended to have colonoscopies every one to two years so that as polyps develop, they can be removed quickly, therefore reducing risk for the development of colorectal cancer. If a person develops too many polyps to remove, which happens in FAP, colectomy (colon removal) can be necessary. The power of knowing about these conditions is that individuals who are affected can then have a personalized screening regiment so that cancers can be caught early or even prevented. Please keep in mind that these are just four of many conditions that can cause colon cancer and polyps.
If you’d like more information about ProMedica Cancer Institute’s Cancer Genetics Program, please call 419-824-5073.
Sarah Adelsperger, MS, LCGC, is a board-certified genetic counselor specializing in cancer. Sarah joined Kelly Morse, MS, LCGC, in the Cancer Genetics Program in May 2015 at ProMedica Cancer Institute–the only program in Northwest Ohio and Southeast Michigan with two licensed and board-certified genetics counselors specializing in cancer genetics.