A look at whether or not oral contraceptives help with ovarian cancer survival. Plus: Do false-positive mammogram results serve as a sign of future breast cancer risk?
A retrospective cohort study by investigators from Mayo Clinic suggests that women with ovarian cancer who have taken oral contraceptives (OCs) may have longer progression-free survival (PFS). Studies of the mechanisms of this protective effect, the authors said, might point to more effective therapies for the disease.
Published in BMC Cancer, the results are based on data from 1398 women with ovarian cancer who were treated at the Mayo Clinic between 2000 and 2013. All of them completed a risk factor questionnaire about their previous use of OCs and the duration of that use. The authors also analyzed clinical data from the patients’ medical records.
Of the women, 827 said they had used OCs. The median duration of use was 60 months and the women who had used the Pill were diagnosed with ovarian cancer at a younger age and had fewer live births than those who had no taken OCs.
A univariate analysis showed that the women who had taken OCs had better overall survival (OS) (hazard ratio [HR] 0.73 [95% confidence interval [CI]; 0.62-0.86; P=0.0002) and better PFS (HR 0.71; 95% CI; 0.61-0.83; P<0.0001) than the women who had not used the Pill. The investigators also performed multivariate analyses, which took into consideration variables such as cancer stage and histology, tumor grade, age at diagnosis, and personal and familial history of breast or ovarian cancer. In those analyses, OC use was associated with a statistically significant likelihood of increased PFS but not with increased OS.
Discussing the plausibility of the association between prior OC use and increased survival in ovarian cancer, the authors commented on possible mechanisms of action. Cessation of ovulation, as has been mentioned in other studies, may spare the ovaries from monthly trauma but the investigators also speculated that it might reduce the exposure of the fimbria to hormones in follicular fluid.
Limitations of the analysis included lack of detail on the OC formulations used by the patients and on how recently the women had taken the Pill. The exact cause of death of many of the patients also was still being documented.
False-positive mammograms and breast cancer risk
A 15-year epidemiologic study suggests that false-positive screening on mammography may have a role in predicting a woman’s risk of subsequent breast. The findings, by researchers from UNC Chapel Hill School of Medicine, were published in Cancer Epidemiology Biomarkers & Prevention.
The investigators based their conclusion on an analysis of data from 1994 through 2009 from the Breast Cancer Surveillance Consortium, a collaborative network of seven mammography registries with linkages to tumor and/or pathology registries. The information was from women aged 40 to 74 years who had a false-positive screening mammogram with a recommendation for additional imaging, a false-positive with a recommendation for a biopsy, or a true-negative with no cancer within 1 year after the examination.
Partly conditional Cox proportional hazards survival models were used to assess the association between a false-positive mammogram and a woman’s risk of subsequent breast cancer, with adjustment for potential confounders. The authors also evaluated changes in risk over time using adjusted survival curves stratified by breast density and false-positive result.
Over the study period, which represented more than 12 million person-years of follow up, 48,735 cancers were diagnosed in the women. Risk of developing breast cancer was increased in women with a false-positive mammogram for whom additional imaging was recommended, compared with women with true-negative mammograms (adjusted hazard ratio (aHR) = 1.39; 95% confidence interval [CI], 1.35-1.44). Risk was also increased in women with false-positive screening who were told to have biopsies (aHR=1.76; 95% CI, 1.65-1.88).
Looking at breast density, the authors found that overall, it did not impact risk, except in women with entirely fatty breasts. The aHRs in them were similar to those in women in the false-positive mammogram groups. Among the women with false-positive screening, the increase in risk of developing breast cancer persisted for 10 years after that testing.