There is a significant body of preclinical, epidemiologic, and randomized data demonstrating that aspirin has anticancer effects.
1-7 Several studies
2,4,8-10 have shown that aspirin use after a diagnosis of colorectal cancer improves colorectal cancer–specific and overall survival. Randomized trials
7 designed to assess the cardiovascular benefits of aspirin demonstrate that allocation to aspirin reduces the risk of distant metastasis when cancer is diagnosed (hazard ratio [HR] 0.69; 95% CI, 0.5-0.95;
P = .02) and on subsequent follow-up in patients without metastasis at diagnosis (0.45; 0.28-0.72;
P < .001), with the largest effects seen for colorectal cancer (HR at diagnosis, 0.36; 0.18-0.74;
P = .005; and HR at follow-up, 0.26; 0.11-0.57;
P < .001). Although questions remain about the optimal dose and duration of aspirin use, its efficacy in prediagnostic users, and the localization of tumors most likely to benefit, the data suggest that aspirin is a potential adjuvant therapy to prevent distant metastasis in colorectal cancer, and possibly other tumors.