Irregular Cycles May Be More Than An Annoyance

It's been a theory that infrequent ovulation may have some beneficial effect at lessening the risk for ovarian cancer. Women who take oral contraceptives, for example, have a lower incidence. This protective effect of irregular cycles may not always hold true. At the recent American Association for Cancer Research (AACR) meeting, Barbara Cohn, Director of Child Health and Development Studies at the Public Health Institute in Berkeley, CA presented some evidence that irregular cycles may actually be a risk factor for later development of ovarian cancer.

Background. Early detection of ovarian cancer has proved elusive, resulting in poor survival. This is the first prospective study to link a common reproductive condition to risk. Polycystic ovarian syndrome (PCOS) is an endocrine disorder, characterized by irregular menstrual cycles with long-term health consequences. Although some women with PCOS are infertile, the majority achieve pregnancy. It has been suggested that women with less frequent ovulation are protected, however, previous reports are inconsistent. Here we examine whether irregular cycling is associated with subsequent ovarian cancer death in a large prospective pregnancy cohort, The Child Health and Development Studies.

Methods. Subjects were 14,403 pregnant women recruited from the Kaiser Permanente Health Plan in 1959-1967 and followed for over 50 years. Menstrual irregularity, cycles >35 days or anovulation, was a proxy for PCOS, identified from medical record and self-report, at a median age of 26 years in 13% of women. Linkage to California Vital Statistics and National Death Index records identified 64 ovarian cancer deaths diagnosed at a median age of 69 years.

Results. Contrary to expectations, women with irregular cycles had a two-fold greater risk of ovarian cancer (Hazard Ratio=2.4; 95% Confidence Interval=1.3,4.5), independent of age, race, parity, and weight. This association was specific to cancer of the ovary - no association was observed for breast or uterine cancer - and it increased over the follow-up period (p=0.08 for time-dependence).

Conclusions. This is the first large prospective study of irregular cycles as an early marker of ovarian cancer. If confirmed, women with irregular cycles could be targeted for screening. This finding offers a strategy to search for antecedent ovarian cancer biomarkers, creating the opportunity for new early detection strategies.

It's not clear what exactly is going on here. Could later cancer be a side effect of abnormal hormone fluctuations? Could this be a receptor issue in the ovary iteslf? Or could the underlying cause of the hormone pathophysiology be the culprit? It's far too soon to know the answer but further research is clearly needed.

At this point, the best advice is to discuss your concerns with your gynecologist. For more information or to schedule an appointment for a pelvic ultrasound, please call: (718) 925-6277.