Colorectal Cancer Health Center

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Magnitude of Effect: The estimated average excess risk of upper gastrointestinal complications in average-risk people attributable to NSAIDs is 4/1,000 to 5/1,000 people per year. The excess risk varies with the underlying gastrointestinal risk, however, it likely exceeds ten extra cases per 1,000 people per year in more than 10% of users. Serious cardiovascular events are increased by 50% to 60%.

Aspirin

Benefits

Based on solid evidence, daily aspirin (acetylsalicylic acid [ASA]) for at least 5 years reduces CRC incidence and mortality. This is based on two reports of extended follow-up of two RCTs [16,17] and meta-analysis of observational studies.[16] A third report that adds extended follow-up of an additional two RCTs (with a meta-analysis of all four RCTs) adds certainty to this conclusion.[18]

Magnitude of Effect: After 23 years of follow-up, incidence of CRC in the placebo group was 3.8% and in the ASA group 2.5% (hazard ratio [HR] = 0.63; 95% CI, 0.47-0.85). In the report from all four RCTs, the 20-year risk of death due to CRC in trials that allocated ASA for at least 5 years was reduced by about 40% (HR = 0.60; 95% CI, 0.45-0.81), absolute risk reduction was from about 3.1% to 1.9%. The primary effect was on mortality from proximal colon cancer.

Harms

Based on solid evidence, harms of ASA use include excessive bleeding, including gastrointestinal bleeds and hemorrhagic stroke.

Magnitude of Effect: The estimated average excess risk of upper gastrointestinal complications is 10 to 30 per 1,000 people for a period of 10 years, on the higher end for men and on the lower end for women. Risk increases with age.

Postmenopausal hormones

Benefits

Based on solid evidence, postmenopausal estrogen plus progesterone hormone use, but not estrogen alone, decreases the incidence of CRC.[21]

Magnitude of Effect: In the Women's Health Initiative (WHI), there was a 44% reduction in CRC incidence in the estrogen and progesterone group but not in the estrogen-only group. The absolute reduction in the incidence of CRC was 0.6 cancers per 1,000 women, from 1.6 cancers per 1,000 women to 1.0 cancer per 1,000 women. A meta-analysis of 18 observational studies showed a 20% reduction in colon cancer incidence among women who had ever used hormone therapy (RR = 0.80; 95% CI, 0.74-0.86) compared with nonusers and a 34% reduction among current users (RR = 0.66; 95% CI, 0.59-0.74).