Ovarian cancer may progress more slowly in women who once used oral contraceptives (OCs) according to a retrospective study of patients treated at the Mayo Clinic in Rochester, MN.1
In a video discussing the findings, lead author Aminah Jatoi, MD, an oncologist with the Mayo Clinic in Rochester MN, explained that whereas previous studies have found OC users were less likely to develop ovarian cancer, she and her colleagues “looked at other factors, specifically the prognosis of people who develop ovarian cancer…Interestingly, we found that those people who had been on OCs actually did better.”
The researchers recruited 1398 women aged 20 years or older who were treated at the Mayo Clinic between 2000 through 2013 for invasive primary epithelial ovarian cancer, fallopian tube cancer, or peritoneal cancer.
The women completed a self-administered questionnaire about their OC use, menstrual history, number of live births, and other hormone-related factors. Using electronic medical records, investigators compiled data on each woman’s cancer diagnosis and histology, surgical and medical treatments, smoking history, and family history of breast or ovarian cancer.
According to the questionnaires, 827 women had used OCs, and the median duration of use was 60 months. Younger women were more likely to report OC use.
Multivariate analyses showed significantly longer progression-free survival for women who had a history of OC use relative to women who had never used OCs (hazard ratio [HR], 0.78; 95% CI, 0.64 – 0.96; P = .02) but showed no significant difference in overall survival between the cohorts.
Univariate analyses suggested a significant advantage for OC users vs never-users in progression-free survival (HR, 0.71; 95% CI, 0.61 – 0.83; P < .0001) and overall survival (HR, 0.73; 95% CI, 0.62 – 0.86; P = .0002), but the overall survival benefit was no longer statistically significant once the researchers adjusted for the women’s age at diagnosis.
The authors did not include data on the type of OC, the timing of OC use relative to the ovarian cancer diagnosis, or the cause of death, which they acknowledged were limitations of the study. In Dr Jatoi’s video discussion, she said the findings were interesting, however, and merited further investigation.
She emphasized the need for other centers to confirm her group’s findings and for studies to determine how OCs might influence the course of ovarian cancer that is diagnosed several years after use. “Is it some change that occurs in the cancer itself as a result of changes in the microenvironment that lead to better outcomes when patients develop this disease?” Dr Jatoi asked.
RELATED: Oral Contraceptives May Protect Against Endometrial Cancer
The study authors offered a few hypotheses for the benefits of OCs on ovarian cancer survival. For example, suppressing ovulation might reduce monthly trauma to the ovary that stimulates epithelial cancer cells to replicate and acquire additional DNA mutations associated with more aggressive cancer.
Another theory is that the hormones used in the contraceptive provoke changes in the extracellular matrix that have long-term effects on the malignant potential of ovarian cancer and its vulnerability to systemic treatments. Dr Jatoi said the answer to these questions could have therapeutic potential. “We might be able to find out ways to intervene once patients have the tumor that result in their…doing better during that period after developing cancer.”
- Jatoi A, Foster NR, Kalli KR, et al. Prior oral contraceptive use in ovarian cancer patients: assessing associations with overall and progression-free survival. BMC Cancer. 2015;15:711.