Long-term prediagnostic aspirin use yields survival benefit in CRC

Among patients with nonmetastatic colorectal cancer (CRC), long-term use of aspirin prior to diagnosis appears to cut the risk of CRC-specific mortality, a study has found.

The prospective study included women and men from the Cancer Prevention Study-II Nutrition Cohort who were cancer-free at baseline (1992 or 1993) and received a CRC diagnosis during follow-up through 2015. All of them completed questionnaires at baseline and every 2 years thereafter to report their use of aspirin and nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs).

The analysis covered pre- and postdiagnosis data for 2,686 and 1,931 participants without distant metastases, respectively, of whom 512 and 251 died from CRC over the follow-up.

Multivariable Cox proportional hazards analysis showed that long-term regular use of aspirin (>15 times per month) prior to diagnosis was associated with lower CRC-specific mortality (hazard ratio [HR], 0.69, 95 percent confidence interval [CI], 0.52–0.92).

Postdiagnosis regular aspirin use, on the other hand, did not alter the risk of CRC-specific mortality (HR, 0.82, 95 percent CI, 0.62–1.09). Nevertheless, patients who initiated regular aspirin use only after their diagnosis were at lower risk than those who did not use aspirin in both the pre- and postdiagnosis periods (HR, 0.60, 95 percent CI, 0.36–0.98).

Finally, patients with long-term aspirin exposure prior to diagnosis were also less likely to have distant metastases (odds ratio, 0.73, 95 percent CI, 0.53–0.99).

The lower CRC-specific mortality associated with long-term aspirin use prior to a diagnosis is consistent with possible inhibition of micro-metastases.