Which of the following is NOT a risk factor for colorectal cancer?

Colorectal cancer is more prevalent in individuals with certain risk factors, which include conditions and behaviors that significantly increase the likelihood of developing the disease. Each of the listed conditions plays a role in this increased risk.

Ulcerative colitis is a well-known risk factor due to its association with chronic inflammation of the colon, which can lead to dysplastic changes and ultimately cancer. Similarly, individuals with a personal history of adenomatous polyps have an increased risk because these polyps are precursors to colorectal cancer; their presence means the patient has already shown a propensity for colonic neoplasia.

Familial adenomatous polyposis (FAP) is a hereditary syndrome that results in numerous adenomatous polyps in the colon and rectum, with nearly a 100% risk of colorectal cancer if left untreated.

Smoking is indeed associated with many forms of cancer, including lung, bladder, and even colorectal cancer, but it is considered a less direct and less significant risk factor in comparison to the other options listed. While a history of smoking does carry some degree of risk for colorectal cancer, it does not have the same strong, established link as the other lifestyle and genetic factors in this context.

Thus, the option of smoking is