Aspirin: Does It Lower Risk for Subtypes of Colon Cancer?

aspirinBackground: Aspirin and related drugs are known to reduce polyp formation for those with familial adenomatous polyposis (FAP), can lower the risk of colorectal cancer among those with Lynch syndrome, and may reduce the risk of colorectal cancer for the general population, too. For those with colorectal cancer, aspirin (and similar drugs)  may improve survival, too. But does everyone with colorectal cancer benefit, or is it just those whose tumors express cyclooxgenase-2 (a target for aspirin therapy)? Recent data indicate this beneficial effect is limited to those with PIK3CA-mutant cancers.

This Study: Researchers in the current study set out to determine the predictive value of PIK3CA mutations for benefit from both cyclooxygenase-2 inhibition and aspirin in 896 patients enrolled in the Vioxx in Colorectal Cancer Therapy: Definition of Optimal Regime (VICTOR) trial. The large, randomized trial compared the effects of rofecoxib (Vioxx, Merck) with placebo after primary colorectal cancer surgery (resection). Researchers compared RFS and OS between rofecoxib therapy and placebo, as well as between the use and nonuse of low-dose aspirin. The investigators evaluated results based on tumor PIK3CA mutation status.

Results: Regular aspirin use post-diagnosis was associated with a decreased rate of colorectal cancer recurrence in those with PIK3CA-mutant cancers (HR=0.11; 95% CI, 0.001-0.832). Researchers did not observe the benefit in patients without PIK3CA mutations (HR=0.92; 95% CI, 0.60-1.42; P=.71). Researchers observed no evidence of greater benefit with rofecoxib therapy in patients with PIK3CA mutations (multivariate adjusted HR=1.2; 95% CI, 0.53-2.72) compared with those with PIK3CA wild-type cancers (HR=0.87; 95% CI, 0.64-1.16).

My Take: First, I would note that the researchers are consultants for the drug company, Bayer. Still, these findings are concordant with recent data and support the prospective investigation of adjuvant aspirin in PIK3CA-mutant colorectal cancer. If confirmed, we might someday routinely recommend the use of aspirin for selected patients with colon cancer. For now, ask your healthcare provider if aspirin is appropriate (or not) for you.

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minutes. Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

Reference: Domingo E. J Clin Oncol. 2013;doi:10.1200/JCO.2013.50.0322.

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Harvard AB Yale MD UPenn Radiation Oncology Radiation Oncologist, Seattle area

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