To the Editor: Dr Chan and colleagues1 reported the results of an observational study of nonsteroidal anti-inflammatory drug (NSAID) use in the Nurses' Health Study (NHS), in which a significant reduction in colorectal cancer–specific mortality was observed with regular postdiagnostic aspirin use (odds ratio, 0.71; 95% confidence interval, 0.53-0.95), but not with prediagnostic use.
Coghill AE, Newcomb PA, Potter JD. Aspirin Use, Colorectal Cancer Survival, and Loss to Follow-up. JAMA. 2009;302(23):2549-2550. doi:10.1001/jama.2009.1824