(April 15, 2014) Prolonged (>35 days), infrequent, or anovulatory menstrual cycles was associated with as much as a two-fold increase in ovarian cancer and more than a three-fold increase in the risk of fatal ovarian cancer, according to a 50-year, prospective follow-up in 14,403 women. The findings were presented at the American Association for Cancer Research annual meeting last week.
Overall, 13% of the women had a history of irregular menses, which was associated with a 37% increased risk of ovarian cancer and more than double the risk of fatal ovarian cancer. The risk was greatest for late-stage, high-grade, and serous tumors, reported Barbara A. Cohn, PhD, of the Public Health Institute in Berkeley, Calif.
The findings came from an analysis of data from the Child Health and Development Studies, which enrolled pregnant women from 1959 to 1967. Study participants self-reported characteristics of their menstrual cycles at a median age of 26. Statistical methods employed in the analysis controlled for subfertility, use of fertility drugs, weight, age, race, and parity. Investigators documented 64 ovarian cancer deaths.
In the overall analysis, irregular menses was not associated with a statistically significant increase in the hazard for ovarian cancer, but was associated with a significantly heightened risk of late-stage cancers at diagnosis. Associations with late-stage serous tumors, high-grade, and high-grade serous tumors all trended toward increased risk.
Irregular menses was associated with an increased risk of serous ovarian cancer death, late-stage serous ovarian cancer death, and a trend toward an increased risk of endometrioid ovarian cancer death.
Researchers said one possible mechanistic explanation for the associations with high-grade serous cancers is increased estrogen exposure during a prolonged follicular phase and lower lifetime progesterone levels.
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