Dr. Peter Rothwell has extensively studied the benefits of daily aspirin on cancer incidence, mortality, and the risk of metastasis. He has just published three articles in Lancet this month that demonstrates a significant reduction in cancer incidence, cancer-related deaths and the risk of cancer metastases with daily aspirin. [1,2,3]
These 3 reports compliment his previous work which demonstrated that the daily ingestion of at least 75 mg of aspirin for at least 5 years decreased the risk of cancer-related mortality.  In this study, he analyzed over 25,000 patients in eight randomized trials and found that there was a statistically significant decreased risk of death from cancer with the daily ingestion of aspirin for at least 5 years (OR 0.79, p = 0.003). The benefit was seen in esophageal adenocarcinoma, lung adenocarcinoma, pancreatic cancer, brain cancer, gastric cancer, breast cancer, biliary cancer, and colorectal cancer. The benefit appeared to increase with the duration of aspirin treatment and appeared to be effective regardless of sex and smoking status. The greatest benefit was seen among adenocarcinomas (HR 0.66).
The recent studies analyzed data from 51 randomized controlled trials involving over 69,000 patients. The results revealed a decreased cancer incidence after 3 years of aspirin usage (OR 0.76, p = 0.003) that applied to both men and women. Although aspirin use decreased the incidence of many types of cancer, the benefit was greatest among gastrointestinal cancers (OR 0.62, p<0.001). The analysis also revealed a significant decrease in distant metastases among aspirin users (OR 0.64, p=0.001). As was seen in cancer incidence, the effect on distant metastases was greatest in adenocarcinomas (HR 0.54, p=0.0007) versus other solid cancers (HR 0.82, p=0.39). It is postulated that the decrease in cancer-related deaths may be due to the prevention of distant metastases.
We already know that daily aspirin is beneficial for primary cardiovascular prevention if the 10-year risk of significant coronary artery disease is at least 10%. This data gives us another reason to recommend daily aspirin use, especially in our patients who have a strong family history of cancer.
Joseph Esherick, MD, FAAFP is the Associate Director of Medicine and the Medical ICU Director at the Ventura County Medical Center in Ventura, California. He is also an Associate Clinical Professor of Family Medicine at The David Geffen School of Medicine at UCLA. He received his medical degree from Yale University School of Medicine, New Haven, Connecticut, and completed a family practice residency at the Ventura County Medical Center, Ventura, California. He is board certified in family medicine and the author of the Tarascon Primary Care Pocketbook and the Tarascon Hospital Medicine Pocketbook. He is one of the lead instructors of the Hospitalist and Emergency Procedures Courses for Hospital Procedures Consultants. He is also an editorial board member for Tarascon Publishing and for Elsevier’s First Consult.
Dr. Esherick is the author of some of Tarascon Publishing’s best-selling titles including:
Tarascon Medical Procedures Pocketbook, Tarascon Hospital Medicine Pocketbookand Tarascon Primary Care Pocketbook. Hospital Medicine and Primary Care are also available for mobile (iPhone, Android and Blackberry).
________________________________________________________________ Rothwell PM et al. Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: analysis of the time course of risks and benefits in 51 randomized controlled trials. The Lancet, March 21, 2012. doi: 10.1016/S0140-6736(11)61720-0  Rothwell PM et al. Effects of regular aspirin on long-term cancer incidence and metastasis: a systematic comparison of evidence from observational studies versus randomized trials. Lancet Oncology, March 21, 2012. Doi: 10.1016/S1470-2045(12)70112-2  Rothwell PM et al. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomized controlled trials. Lancet, March 21, 2012. Doi: 10.1016/S0140-6736(12)60209-8.  Rothwell PM et al. Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomized trials. Lancet, 2011; 377 (9759): 31-41.