Long-Term Aspirin Use May Lower Risk of Ovarian Cancer

NASHVILLE—Long-term aspirin use may decrease the risk of epithelial ovarian cancer, Arslan Akhmedkhanov, MD, reported at the 32^nd Annual Meeting of the Society of Gynecologic Oncologists (SGO). The study involved 748 patients from a prospective cohort followed for an average of 12 years.

Initial results suggest that aspirin use three or more times a week for at least 6 months could be associated with a 40% reduction in the risk of developing epithelial ovarian cancer, said Dr. Akhmedkhanov, research assistant professor, Division of Women’s Health Epidemiology, Department of Obstetrics and Gynecology, New York University (NYU) School of Medicine.

"Evidence suggests that chronic inflammation, similar to the inflammation seen in endometriosis and pelvic inflammatory disease, could be related to epithelial ovarian cancer," he said. "One way to evaluate the role of inflammation in ovarian cancer is to examine the effect of common anti-inflammatory medications, such as aspirin, on epithelial ovarian cancer risk. Our data, combined with other similar research, indicate that aspirin may have broader anticarcinogenic properties than previously thought."

The subjects came from NYU’s Women’s Health Study, a long-term prospective cohort involving more than 14,000 women who completed a health questionnaire at enrollment (between 1985 and 1991) and every 2 years thereafter.

Of this cohort, 12,239 women responded to baseline and 1994-1996 follow-up questionnaires. The 1994-1996 follow-up collected data on aspirin use via the following question: "Have you taken aspirin three or more times per week for a period of 6 months or longer?" For women who answered yes, information regarding the dose and duration of aspirin use was gathered.

A total of 140 women with ovarian cancer were identified in the cohort after an average follow-up of 12 years. Of these, 55 were excluded because the cancer diagnosis preceded enrollment in the study. Of the remaining 85 cases, 73 responded to questions on aspirin use in the 1994-1996 questionnaire. Among the confirmed cases, 5 were excluded because they were nonepithelial ovarian cancer.

The remaining 68 cases of epithelial ovarian cancer were included in this nested case-control study. For each case, 10 matched controls were selected at random from cancer-free cohort members.

Within each matched set, aspirin exposure was discounted for both cases and corresponding controls if it occurred after, or within 1 year before, the date of case diagnosis. A lag period of 1 year was chosen, Dr. Akhmedkhanov said, to prevent the possibility that aspirin use among the cases might have been the result of early symptoms of an undiagnosed disease "and therefore might be a consequence of, rather than a risk factor for, disease."

Study Results

Results showed that taking aspirin three or more times a week for at least 6 months appeared to be inversely associated with the risk of epithelial ovarian cancer, with an odds ratio of .60 (adjusted for potential risk factors). This corresponds to a 40% reduction in risk, Dr. Akhmedkhanov said.

The protective effect may be stronger among recent users of aspirin (use within the previous 5 years). For this group the adjusted odds radio was .36, he said.

He noted that the results should be interpreted with caution, because of the study limitations. Among them, the study was based on a limited number of cases, "and we did not have information on the exact dosage and indications for aspirin use, which should be taken into account," he said. Therefore, at this time, Dr. Akhmedkhanov said, "we cannot recommend that women start taking aspirin to prevent ovarian cancer based on the results of this study alone. Larger studies are needed to confirm this effect and clarify the effective dose and duration."