By: Dan Sperling, MD
Evidence from epidemiology (population data) suggests that the daily use of aspirin commonly taken by patients at risk for stroke or heart attack as a low-dose anticoagulant (AC) or blood thinner helps prevent recurrence of certain types of colorectal cancer.
The means by which aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) reduce recurrence rates in colorectal or any other cancer such as lung or breast cancer are incompletely understood. Furthermore, longterm use of NSAIDs carries risks of adverse side effects. Because of this, oversight bodies have avoided recommending widespread aspirin use by the general population as a way to prevent colorectal or any other type of cancer except for certain high-risk patients. Nonetheless, early data “suggests that aspirin may not only prevent certain cancers, but also influence the biology of established disease.”[i] This observation has raised interest in the potential of daily aspirin and other AC use to reduce the chance of prostate cancer recurrence after treatment.
Two studies were published in 2012 that shed light on the hypothesis that aspirin use after prostate cancer surgery or radiation can inhibit recurrence.
The first examined early biochemical failure (rising PSA less than 18 months after treatment) following prostate radiation therapy (18 months being an interval “shown to be the single strongest predictor of distant metastases.”)[ii] The authors used retrospective data from 2051 men with clinically localized PCa who received radiation therapy, tracking patients who were using aspirin (36% of patients) or any cholesterol-controlling drugs known as statins (34%). Median follow-up was 75 months. The authors found that aspirin non-use, followed by statin non-use, were the two variables most closely linked with biochemical failure. This includes data on Gleason score, patient age, radiation dose or tumor stage. The authors wrote that among the patients, lack of aspirin or statin use was a “harbinger of distant metastasis and death,” and encouraged further study to explore how much aspirin and how often would be optimal, as well as any risks associated with such use. The results of this analysis are consistent with an earlier University of Chicago study (2009) that found that prostate cancer patients who received either beam radiation or brachytherapy and used anti-clotting drugs, most notably aspirin, had a 46% reduced risk of recurrence over those who did not take ACs.[iii]
The second article pooled clinical data on 5,955 prostate cancer patients from the CAPSURE database, including those who were treated with either radical prostatectomy or radiation therapy.[iv] Out of the nearly six thousand subjects, 37% were using some type of blood thinner (warfarin, clopidogrel, enoxaparin, and/or aspirin). The authors compared those using blood thinners with patients who were not on anticoagulants regarding death rates from prostate cancer. With an average of 70 months follow-up, the researchers found that risk of death from prostate cancer was significantly lower in the blood thinner patients than in those who were not using the drugs. The reduction in risk was greatest among those with high-risk disease, regardless of treatment modality. Of the types of anticoagulants, aspirin provided the greatest benefit, noting that “aspirin use was independently associated with a lower risk of PCSM [prostate cancer specific mortality]…”
It therefore appears that using aspirin provides a mechanism whereby the potential for prostate cancer recurrence after treatment by either radiation or prostatectomy is significantly lowered. Keeping in mind that no dosage has been established, nor long term side effects tracked, taking aspirin seems to be a safe and inexpensive way to increase post-treatment survival.
[ii] Zaorsky NG1, Buyyounouski MK, Li T, Horwitz EM. Aspirin and statin nonuse associated with early biochemical failure after prostate radiation therapy. Int J Radiat Oncol Biol Phys. 2012 Sep 1;84(1):e13-7.