Studies have shown that combination hormone replacement therapy (HRT) that includes both estrogen and progesterone lowers the risk of invasive colorectal cancer in postmenopausal women. However, combination HRT does not lower the risk of dying from colorectal cancer.
Not all hormone replacement therapy decreases the risk of having colorectal cancer. HRT with estrogen alone does not lower the risk of having invasive colorectal cancer or the risk of dying from colorectal cancer.
The possible harms of hormone replacement therapy include an increased risk of having:
- Breast cancer.
- Heart disease.
- Blood clots.
Most colorectal polyps are adenomas, which may develop into cancer. Removing colorectal polyps that are larger than 1 centimeter (cm) may lower the risk of colorectal cancer. It is not known if removing smaller polyps lowers the risk of colorectal cancer.
The possible harms of polyp removal during colonoscopy or sigmoidoscopy include a tear in the wall of the colon and bleeding.
Polyps in the colon. Some polyps have a stalk and others do not. Inset shows a photo of a polyp with a stalk.
The effect of the following factors on the risk of colorectal cancer is not known:
Nonsteroidal anti-inflammatory drugs (NSAIDs) other than aspirin
It is not known if the use of nonsteroidal anti-inflammatory drugs or NSAIDs (such as celecoxib, naproxen, and ibuprofen) lowers the risk of colorectal cancer.
Studies have shown that taking the nonsteroidal anti-inflammatory drug celecoxib reduces the risk of colorectal adenomas (benign tumors) coming back after they have been removed. It is not clear if this results in a lower risk of cancerous tumors in the colon and rectum. Taking celecoxib also has been shown to reduce the number of polyps that form in the colon and rectum of patients with familial adenomatous polyposis (FAP).
The possible harms of NSAIDs include:
- Kidney problems.
- Bleeding in the stomach, intestines, or brain.
- Heart problems such as heart attack and congestive heart failure.
It is not known if a diet low in fat and meat and high in fiber, fruits, and vegetables lowers the risk of colorectal cancer.