Many studies have found that use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced risk of several cancers and precancerous lesions. Past studies in human cells and in laboratory animals have suggested that aspirin and NSAIDs may inhibit the development of pancreatic cancer. However, few studies have examined the association between analgesic use and pancreatic cancer in humans, and results have been inconsistent.
Eva S. Schernhammer, M.D., Dr.P.H., of the Brigham and Women's Hospital and Harvard Medical School in Boston, and her colleagues examined the association between aspirin use and risk of pancreatic cancer among 88,378 women participating in the Nurses' Health Study. The information used in the study was based on questions about aspirin use asked on biennial questionnaires beginning in 1980. Among those women, 34% were current regular aspirin users, defined as women who took two or more 325 mg aspirin tablets per week. The remaining women were non-regular aspirin users who took less than 2 tablets per week.
During 18 years of follow-up, there were 161 new cases of pancreatic cancer. Overall, there was no statistically significant difference in risk of pancreatic cancer between aspirin users and nonusers. However, when the investigators examined the information based on the duration that the women had been taking aspirin, they found that women who reported more than 20 years of regular aspirin use had a 58% increased risk of pancreatic cancer compared with women who never regularly consumed more than two aspirin tablets per week.
When the investigators compared women who had reported consistent, regular aspirin use with women who were non-users during the same time period, they found that the risk of pancreatic cancer increased with increasing aspirin dose. Compared with nonusers, women who took 14 or more aspirin tablets per week had an 86% increased risk of pancreatic cancer.
"Our findings do not support a protective effect of analgesics use on the risk of pancreatic cancer. Rather, aspirin appears to increase the risk of pancreatic cancer after extended periods of use," the authors write. "Risks and benefits associated with the use of aspirin have to be weighed carefully in any recommendations made by health care providers."
In an accompanying editorial, John A. Baron, M.D., of Dartmouth Medical School, writes, "There are no easy answers to the question of what aspirin and other NSAIDs do to pancreatic carcinogenesis. The findings by Schernhammer et al. are provocative and force us to think carefully about the actions of aspirin and other NSAIDs and the mechanisms underlying pancreatic cancer. Fortunately, conflicting data from diverse threads of research are often a very effective push toward scientific progress."
Schernhammer ES, Kang J, Chan AT, Michaud DS, Skinner HG, Giovanucci E, et al. A prospective study of aspirin use and the risk of pancreatic cancer in women. J Natl Cancer Inst 2003;96:22-8.
Editorial: Baron JA. What now for aspirin and cancer prevention? J Natl Cancer Inst 2003;96:4-5.
Note: The Journal of the National Cancer Institute is published by Oxford University Press and is not affiliated with the National Cancer Institute. Attribution to the Journal of the National Cancer Institute is requested in all news coverage. Visit the Journal online at http://jncicancerspectrum.