The first prospective study to link reproduction to ovarian cancer risk found that a history of irregular menstrual cycles at age 26 predicted the eventual development of aggressive ovarian cancer. In fact, women with irregular menses had as high as a 2-fold increase in the risk of ovarian cancer and a more than 2-fold increase in the risk of ovarian cancer death.
These findings are important, said lead author Barbara A. Cohn, PhD, MPH, of the Public Health Institute in Berkeley, California, because by the time most ovarian cancers are detected, they are already symptomatic and aggressive. “These data are the first solid lead we’ve had that has potential for earlier diagnosis. This is an opportunity to identify underlying mechanisms and ways to prevent the 90% of sporadic ovarian cancers that occur without known heritable risk,” she added.
“The devil is in the details,” Cohn said. “We defined ‘irregular’ as cycles longer than 35 days or anovulatory menstrual cycles. In other words, these women could not predict when their menses was coming.”
The study enrolled only pregnant women in order to rule out the effect of fertility drugs and infertility on the risk of developing ovarian cancer. As part of the Child Health and Development Studies, 14,403 pregnant women were recruited from 1959 to 1967. At baseline (median age, 26 years), women were asked to characterize their menstrual cycles. Thirteen percent reported irregular menses according to the definition Cohn described. These data were linked to California Vital Statistics and National Death Index files to detect 103 cases of ovarian cancer, histology, stage, grade, and mortality (there were 65 deaths).
Women with irregular cycles had a 37% increased risk of developing ovarian cancer and more than a 2-fold increase in ovarian cancer death due to more late-stage disease and more aggressive histology at diagnosis. The risk was greatest for late-stage, high-grade, and serous tumors, Cohn said.
In the overall analysis, irregular menses was associated with a 2.3 times greater risk of ovarian cancer death (P = .01) and a 3 times greater risk of death from late-stage serous ovarian cancer (P = .01). The risk of developing late-stage or high-grade serous ovarian cancer was also significantly increased among women with a history of irregular menses (P = .02 and P = .07, respectively).
Although these findings are hypothesis generating, Cohn said that young women with irregular menses might consider taking birth control pills. “Birth control pills seem to be protective and regularize menstrual cycles. Of course, this decision should be made in consultation with a physician, and individual risk factors need to be considered as well,” Cohn noted. l
Cohn BA, Cirillo PM, Wang ET, et al. Irregular menstruation predicts increased risk of subsequent ovarian cancer death in a prospective cohort, The Child Health and Development Studies. Presented at: 2014 Annual Meeting of the American Association for Cancer Research; April 5-9, 2014; San Diego, CA. Abstract LB-277.