Acetaminophen Use May Cut Risk of Prostate Cancer

New findings suggest that long-term, regular acetaminophen use may be associated with a lower risk of prostate cancer. Researchers from the American Cancer Society in Atlanta, Georgia, found that men who reported taking ≥30 acetaminophen pills per month for at least 5 years had a nearly 40% lower risk of prostate cancer than men who did not report regular acetaminophen use.

Eric J. Jacobs, PhD, and colleagues examined the association between acetaminophen use and prostate cancer incidence in 78,485 male participants in the Cancer Prevention Study II (CPS-II) Nutrition Cohort. Initiated in 1992, the CPS-II Nutrition Cohort is a prospective study of cancer incidence in the United States that included men aged 50 to 74 years who resided in 21 states with population-based state cancer registries.

The researchers pointed out that the use of aspirin and other nonsteroidal antiinflammatory agents (NSAIDs) has been associated with a slightly lower risk of prostate cancer in epidemiological studies. Acetaminophen is not typically considered an NSAID; however, the medication has been shown to have anti-inflammatory properties in studies of osteoarthritis and dental surgery patients and in experimental studies. While multiple studies have looked at the link between NSAID use and prostate cancer, they said that relatively few studies have looked at the use of acetaminophen, which is commonly taken as a pain reliever.

At enrollment in 1992 or 1993, participants completed a self-administered questionnaire focusing on demographic, medical, and lifestyle factors. Follow-up questionnaires were sent in 1997 and every 2 years thereafter in order to obtain an update on exposure information and to ascertain newly diagnosed cancers. Regular aspirin use was defined as ≥30 pills per month and long-term use referred to aspirin use of ≥5 years. During the 15-year follow-up period, 8092 incident prostate cancer cases were identified.

It is "biologically plausible" that acetaminophen use may decrease prostate cancer risk by blocking chronic inflammation, which is thought to increase prostate cancer risk.

Current regular use of aspirin for ≥5 was associated with a lower risk of overall prostate cancer (RR = 0.62; 95% CI, 0.44-0.87) and aggressive prostate cancer (RR = 0.49; 95% CI, 0.27- 0.88). Shorter-term aspirin use was not associated with an increased risk of prostate cancer. Although arthritis is a major indication for acetaminophen use, neither rheumatoid arthritis nor oseoarthritis was associated with prostate cancer risk.

Jacobs and colleagues said that important study strengths include its large size, prospective design, and the ability to identify long-term regular acetaminophen users based on successive questionnaires. On the other hand, the prevalence of long-term regular acetaminophen use was low, making it difficult to provide a precise risk estimate. Potential confounding by factors associated with both acetaminophen use and prostate cancer risk is also a potential drawback.

They added that the biological mechanisms through which acetaminophen may inhibit prostate carcinogenesis are not yet known, but it is "biologically plausible" that acetaminophen use may decrease prostate cancer risk by blocking chronic inflammation, which is thought to increase prostate cancer risk.

Finally, they emphasized that it is too early to advocate long-term, regular aspirin use to lower prostate cancer risk. It is also important to keep in mind that acetaminophen use may cause liver damage but is considered relatively safe when used at recommended doses.

Jacobs EJ, Newton CC, Stevens VL, Gapstur SM. A large cohort study of long-term acetaminophen use and prostate cancer incidence [published online ahead of print May 17, 2011]. Cancer Epidemiol Biomarkers Prev. doi:10.1158/1055- 9965.EPI-11-0210