Colorectal cancer typically starts as a benign tumor, often in the form of a polyp. © Shutterstock.
Colorectal cancer, also known as bowel cancer, colon cancer or rectal cancer, is a cancer that starts in the colon (large intestine) or rectum. It is the third most common type of cancer worldwide, estimated to make up about 10% of all cancer cases. Most colorectal cancers are associated with old age and lifestyle factors, with less than 5% of cases linked to inherited genes. The most common inherited syndromes that increase colon cancer risk are familial adenomatous polyposis (FAP) and Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC). How can people at high genetic risk for colorectal cancer reduce their chances of developing the disease? They could benefit from leading a healthy lifestyle, says a study by Vanderbilt researchers.
In fact, people with a high polygenic risk score for colorectal cancer showed a greater benefit from leading a healthy lifestyle than those at lower genetic risk. Maintaining a healthy lifestyle was found to be associated with a nearly 40% reduction in colorectal cancer risk among those with a high genetic risk of developing the disease, as compared to only about 25% among people at a low genetic risk for this cancer. But people with a low genetic risk and a healthy lifestyle were more than three times less likely to be diagnosed with colorectal cancer than people with a high genetic risk and an unhealthy lifestyle.
The study findings could help in designing personalized prevention strategies for colorectal cancer prevention, said Wei Zheng, MD, PhD, MPH, Anne Potter Wilson Professor of Medicine and associate director for Population Sciences Research at Vanderbilt-Ingram Cancer Center (VICC). The results were published in the April issue of The American Journal of Clinical Nutrition.
In its new recommendation, the U.S. Preventive Services Task Force has suggested beginning screening for colorectal cancer at age 45 instead of 50. Starting routine screening five years earlier could prevent more deaths from colorectal cancer, it said in the recommendation published in the journal JAMA. The expert panel recommended two types of tests for colorectal cancer screening: Direct Visualization Tests (which include colonoscopy, CT colonography, and flexible sigmoidoscopy) and Stool-Based Tests (which include the high-sensitivity guaiac fecal occult blood test (gFOBT), fecal immunochemical test (FIT), and stool DNA test.)
While colorectal cancer is most frequently diagnosed in people aged 65 to 74 years, about 10.5% of new cases occur in persons younger than 50 years, the experts pointed out.
Apart from underlying genetic disorders, other risk factors for colorectal cancer include diet, obesity, smoking, and lack of physical activity. Dietary factors linked to increased risk for this type of cancer include red meat, processed meat, and alcohol. Inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis, is another risk factor for the disease.
Colorectal cancer typically starts as a benign tumor, often in the form of a polyp and gradually becomes cancerous. If you notice blood in the stool, a change in bowel movements, weight loss, and fatigue, see a doctor. These are considered as signs and symptoms of colorectal cancer. Colorectal cancer may be treated with a combination of surgery, radiation therapy, chemotherapy and targeted therapy.
