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Oral contraceptive birth control reduces risk for aggressive ovarian cancer
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ATLANTA — Oral contraceptive use appeared associated with a reduced risk for highly fatal aggressive ovarian cancer, with a greater risk reduction observed with longer birth control use, according to study results presented at American Association for Cancer Research Annual Meeting.
Although it has been known that oral contraceptive use reduces the risk for ovarian cancer, this is the first study to show the risk reduction is driven by a lower incidence of aggressive and highly fatal subtypes of ovarian cancer.
“The longer the history of oral contraceptive use, the greater the protection we observed in terms of reduced chance of dying [of] aggressive ovarian cancer,” Jennifer M. Mongiovi, graduate student at Roswell Park Comprehensive Cancer Center and cancer epidemiology fellow in the department of epidemiology and environmental health at University at Buffalo, said in a press release. “For every 5 years of use, we observed 32% lower odds of highly fatal disease, compared to 13% for all ovarian cancer as previously reported by other researchers. This association also varies by histological subtype, and was found most protective for highly fatal endometrioid ovarian cancers.”
Mongiovi and colleagues used data from 20 case-control studies in the Ovarian Cancer Association Consortium to evaluate the association between prediagnostic oral contraceptive use and highly fatal ovarian cancer, defined as mortality within 12 or 18 months of diagnosis.
The analysis included 579 women who died within 12 months of their diagnosis, matched 1:4 by 5-year age categories, race and study site to 2,279 controls, as well as 1,294 patients who died within 18 months matched to 5,095 controls.
Analyses adjusted for age, site and parity showed any oral contraceptive use was associated with a 46% reduction in the odds of death within 12 months (OR = 0.54; 95% CI, 0.43-0.68).
Researchers then conducted separate models for duration of oral contraceptive use per 5-year increase. Results showed a 66% reduction in odds of death within 12 months for those who used oral contraceptives for more than 10 years (OR = 0.34; 95% CI, 0.23-0.49), whereas there was no significant risk reduction for those who used oral contraceptives for 1 year or less (OR = 0.83; 95% CI, 0.6-1.14).
These trends appeared consistent among women who died within 18 months; however, oral contraceptive use appeared more protective among highly fatal cases, or those who died within 12 months.
Use of oral contraception appeared most protective for endometrioid subtypes among those who died within 12 months (OR = 0.43, 95% CI, 0.2-0.93) and 18 months (OR = 0.39, 95% CI, 0.23-0.65).
“Our results provide strong evidence that this is an area worthy of further study so that we can better understand the mechanisms behind this association and identify specific groups of people who may benefit most from this chemopreventive strategy,” senior author Kirsten Moysich, PhD, MS, distinguished professor of oncology in the departments of cancer prevention and control and immunology at Roswell Park, said in the press release. – by Alexandra Todak
Reference:
Mongiovi JM, et al. Abstract 641/25. Presented at: AACR Annual Meeting; March 29-April 3, 2019; Atlanta.
Disclosures: The authors report no relevant financial disclosures.
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Kristin Anderson, PhD
The findings of this study are interesting because they suggest that reducing the number of ovulations a woman experiences may correlate with reducing the aggressiveness of disease when it develops. The correlation between oral contraceptive use and reduced risk for developing ovarian cancer has been known for some time, both for women with BRCA1/BRCA2 mutations and for the general population. This study instead focused on women who had been diagnosed with ovarian cancer, and it suggests that patients may have better survival if they used oral contraceptives over a long period of time prior to diagnosis, an interesting and provocative finding.
Every time a woman ovulates, damage to the ovary and inflammation occurs, and the working hypothesis in the field is that this inflammation may promote cancer growth and aggressiveness. Because women who regularly use oral contraceptives have fewer ovulations over time, this likely results in fewer inflammatory events, which may be why regular oral contraceptive use is correlated with reduced risk for disease development. This study takes that correlation one step further and suggests that among women who develop ovarian cancer, use of oral contraceptives may have played a role in reducing the aggressiveness of their disease. Reduced inflammation over time could explain this correlation as well.
These results are provocative — if oral contraceptive use both reduces the incidence of disease development and reduces the aggressiveness of disease when it develops, this may influence how providers consider discussing oral contraceptive use with all women, not just those at high risk. It would be interesting to know the mechanism behind this observation, and also if this correlation is stronger in women with certain types of ovarian cancer.
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