What is Rectal Cancer?
Rectal cancer is a type of cancer that begins in the rectum, which is the last several inches of the large intestine closest to the anus. It typically starts as a growth on the inner lining of the rectum called a polyp, which can eventually turn into cancer. The most common type of rectal cancer is called adenocarcinoma, which starts in the cells that make mucus that covers the inside of the colon and rectum.
Rectal cancer typically affects older adults, though the incidence of colorectal cancer in individuals under 50 has been steadily rising by approximately 2% to 3% per year over the past two decades. It usually begins as small, noncancerous (benign) clumps of cells called polyps that form on the inside of the colon. Over time, some of these polyps can become colon cancers. Undetected and untreated, it could metastasize (spread) to other parts of the body. Because it can take up to ten years for a polyp to become cancerous; regular screenings are critical to prevention and early detection.
According to the American Cancer Society, colorectal cancer is the third most common cancer diagnosed in the United States. About 108,860 new cases of colon cancer (55,410 in men and 53,450 in women) and 49,990 new cases of rectal cancer (28,750 in men and 21,240 in women) are estimated to be diagnosed in 2026. Rectal cancer affects more people who are Black than people who are members of other ethnic groups or races.
Risk Factors
- Age: Most rectal cancer cases are diagnosed in people over age 55. The median age at diagnosis is 66 years old. Diagnosis in people under the age of 50 has increased in recent years.
- Race: Black and African Americans have the highest rate of rectal cancer among all racial groups in the United States.
- Gender: Rectal cancer is slightly more common in men and people assigned male at birth (AMAB) than in women and people assigned female at birth (AFAB).
- Family History: People whose relatives have had colorectal cancer or colorectal polyps have an increased risk of rectal cancer.
Other Medical Conditions
- Inflammatory Bowel Disease (IBD): Conditions such as ulcerative colitis or Crohn’s disease can increase the risk of PSC and, subsequently, rectal cancer.
- Diabetes: Some studies suggest that diabetes may increase the risk of rectal cancer.
- History of Colorectal Cancer or Polyps: People who have previously had rectal cancer or colon polyps are at an increased risk of developing rectal cancer.
- Genetic Predispositions: Certain inherited syndromes, such as Lynch syndrome (hereditary nonpolyposis colorectal cancer) and familial adenomatous polyposis (FAP), significantly increase the risk of rectal cancer
Lifestyle Factors
- Obesity: Obesity increases a person’s chances of developing many different diseases, including rectal cancer.
- Sedentary Lifestyle: A lack of movement and exercise is a risk factor for rectal cancer.
- Diet: A diet heavy in red meat, processed meats, or meats cooked at very high heat can increase a person’s rectal cancer risk.
- Smoking: Tobacco use, including cigarettes and chewing tobacco, is a rectal cancer risk factor.
- Alcohol Use: Heavy drinkers are at an increased risk for rectal cancer.
While these factors can increase the risk, having one or more of them does not mean that someone will develop rectal cancer. Regular screenings and discussing any concerns with a healthcare provider are important for prevention, early detection, and management of rectal cancer.