Aspirin and Prevention of Cancer
Dr. Martin Edelman, professor of medicine at the University of Maryland School of Medicine and director of Solid Tumor Oncology at the University of Maryland Greenebaum Cancer Center, comments on the results of a study published in The Lancet, which found that aspirin was successful in preventing the occurrence of solid tumors for a variety of cancers, including lung cancer, esophageal cancer and colorectal cancer. Dr. Edelman provides a brief overview of the study and provides some perspective on the implications of the study results for cancer prevention guidelines in the future.
Will the increasingly high-tech war against cancer include aspirin—one of the oldest, least expensive medications around? A trio of new studies from the University of Oxford suggests that aspirin is worth testing as a simple way to help prevent cancer. But these are preliminary findings, and you shouldn’t start taking an aspirin a day without having a conversion with your doctor. That’s because aspirin has side effects that could offset any possible cancer-fighting benefit. 
Taking a low dose of aspirin each day may prevent cancer and stop it spreading, according to three papers to be published in leading medical journals on Wednesday. It could also possibly have a use as a treatment for the disease.
Dr Peter Rothwell from Oxford University and the John Radcliffe hospital and colleagues, the authors of the studies in the Lancet and Lancet Oncology have previously shown that long-term daily aspirin, for 10 years or so, reduces the risk of colorectal (bowel) cancer and other common cancers, but some experts have voiced concerns over potential long-term side-effects, because aspirin can cause stomach bleeding. 
Aspirin has also been shown to reduce the risk of colorectal cancer and colorectal polyps. Although taking aspirin daily has some promising benefits, it can also raise the risk of gastrointestinal bleeding.
The report released this week looked at recent studies of aspirin’s impact on cancer prevention. In March, two studies published in the Lancet and one in Lancet Oncology suggested that aspirin could have protective effects against various types of cancer.
“Recently published meta-analyses of results from randomized trials of daily aspirin treatment to prevent vascular events... have provided provocative evidence that daily aspirin at doses of 75 mg and above might lower both overall cancer incidence and overall cancer mortality,” wrote Michael Thun, vice president emeritus of epidemiology and surveillance research for the American Cancer Society and the co-authors in the article.