Genetics play a large part in increasing an individual’s risk of developing bowel cancer. We typically inherit two copies of each gene, one from our mother and one from our father.
If the bowel cancer syndrome is dominant, then only one copy of the altered gene needs to be passed on for the child to inherit the increased risk of bowel cancer.
For example, if a father has a mutated gene, there is a 50% chance of it being passed on to his children should it be dominant. However, not all carriers of this gene will develop cancer.
It can also be passed down in a recessive way, which means two recessive mutated genes are passed on from each parent. Another hereditary condition is the development of bowel polyps. There are two types of bowel polyps adenomas or hyperplastic
A bowel polyp, is a small growth that forms on the inside lining of the colon. Most bowel polyps develop in older people. Polyps are benign, which means they are non-cancerous, and often cause no problems. However, sometimes a benign polyp can turn cancerous, and this change usually takes place after a number of years. Most colorectal cancers develop from a polyp that has been present for at least 5-15 years.
FAP stands for Familial Adenomatous Polyposis and is a rare disease that runs in families, and accounts for 1 out of every 100 bowel cancers. FAP causes multiple small non-cancerous cells (polyps) to grow in the large bowel. While they may seem harmless, many of these can develop into cancer over a period of time. It is recommended in some cases, that those with FAP have their colon removed by age 25, as they have so many polyps it massively increases their chances of getting bowel cancer later on. Although it is largely a hereditary gene, it is possible to have FAP even though there are no cases of it in your family. The gene mutation comes about by accident in about 1 in 4 cases (25%) and not because you’ve inherited it.
HNPCC (lynch Syndrome)
HNPCC (hereditary non polyposis colorectal cancer) is another rare gene mutation that runs in some families, it is also known as Lynch syndrome. If you possess the faulty gene of HNPCC, your risk of later developing many different cancers, including bowel cancer, is increased. The healthy form of this gene helps DNA to repair itself. Because it is rare, HNPCC is probably only responsible for between 1 and 4 out of every 100 bowel cancers diagnosed. HNPCC is particularly linked to bowel cancer that develops at a young age. It probably causes about 4 out of 10 bowel cancer cases (40%) in people under 30.
Hyperplastic polyposis is a rare syndrome characterized by the development of multiple colorectal serrated lesions, most often a mixture of hyperplastic polyps and flat serrated adenomas. Patients with hyperplastic polyposis syndrome (HPS) have a very high lifetime risk of developing colorectal cancer. However, it is not uncommon for the diagnosis to be missed during a colonoscopy, as the flat lesions are not recognized, or the endoscopist is simply unaware of this syndrome.
Most hyperplastic polyps are found in the distal colon and rectum. Although thought to exhibit no malignant potential it has been shown that hyperplastic polyps on the right side of the colon do exhibit a malignant potential, which means that they are no more likely than normal tissue to eventually become a cancer.