Colorectal cancer develops when epithelial cells in the colon and rectum lining grow abnormally and uncontrollably, forming malignant tumors. Doctor Kim Thi Be Diep, from the Oncology Department, Oncology Center, Tam Anh Hospital TP HCM, states that most colorectal cancers originate from adenomatous polyps, which are precancerous lesions. The progression from an adenomatous polyp to invasive cancer often occurs silently, potentially taking about 10-15 years.

Several genetic syndromes increase the risk of colorectal cancer; the most common are hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome, and familial adenomatous polyposis (FAP).

Lynch syndrome

Lynch syndrome results from mutations in several gene, including MLH1, MSH2, MSH6, PMS2, and EPCAM. This condition involves a defect in the DNA mismatch repair (MMR) system due to germline mutations in MMR gene.

Doctor Diep consults a patient. Illustration: Tam Anh General Hospital

Patients with hereditary colorectal cancer due to Lynch syndrome are often diagnosed at a young age. The risk of developing colorectal cancer for individuals with Lynch syndrome ranges from 10% to 80%, according to Doctor Diep. The incidence rate gradually increases depending on the gene mutation causing the syndrome. Lynch syndrome is also a risk factor for several other cancers, such as endometrial, ovarian, small intestine, pancreatic, gastric, kidney, prostate, and breast cancers.

If a family member carries a gene mutation associated with Lynch syndrome, Doctor Diep advises relatives to undergo genetic testing or screening via colonoscopy. Screening is typically recommended every one to two years starting at age 20, or two to five years before the youngest age of cancer diagnosis in an affected relative.

Familial adenomatous polyposis

Familial adenomatous polyposis results from an APC gene mutation inherited from parents, accounting for approximately 1% of colorectal cancer cases. Individuals with FAP have an elevated risk of developing gastric, small intestine, pancreatic cancer, and some other cancers.

Those with this syndrome develop numerous polyps in the colon and rectum, often starting between ages 10 and 12. Cancer typically develops from one of these polyps, potentially as early as age 20. Individuals with genetic test results showing FAP-related gene changes should begin colonoscopy screening between ages 10 and 15. Additionally, close relatives (siblings and children) should undergo genetic testing.

Some less common genetic syndromes associated with colorectal cancer include Peutz-Jeghers syndrome, MUTYH-associated polyposis, and cystic fibrosis, caused by CFTR gene mutations.

Colorectal cancer screening helps detect precancerous lesions or early-stage malignant lesions, allowing for timely treatment and contributing to improved survival rates. Everyone should maintain a healthy lifestyle by not smoking, limiting alcohol consumption, and avoiding excessive processed, fatty foods to reduce disease risk.

Bao Tram