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Women with Irregular Menstrual Cycles at Increased Risk of Ovarian Cancer Death

April 20, 2016

Oakland, CA (April 20, 2016) — Women with irregular menstrual cycles had up to a threefold increased risk of developing ovarian cancer and dying from it, according to a large, prospective study from the Public Health Institute published online this week by the International Journal of Cancer.

The peer-reviewed study confirms preliminary findings presented at the American Association of Cancer Research’s 2014 annual meeting, and additionally finds that the risk of ovarian cancer mortality and incidence increases with age.

“Our study finding is significant because ovarian cancer is usually not diagnosed until after it has spread. There are no reliable early diagnosis or screening methods, and symptoms often go unnoticed until it’s too late,” said Barbara A. Cohn, Ph.D., M.P.H., director of the Public Health Institute’s Child Health and Development Studies (CHDS).

“Discovering high-risk traits like irregular menstruation gives clinicians the opportunity to potentially save lives by identifying them as early warning signs and developing strategies to reduce these women’s risk of death.”

Ovarian cancer accounts for approximately three percent of all cancers in women in the U.S., yet it is the fifth leading cause of cancer death among those women, according to the Centers for Disease Control and Prevention. It causes more deaths than any other reproductive cancer.

This study provides the first prospective evidence that women with irregular menstrual cycles are at higher risk of ovarian cancer. By age 70, the researchers found a twofold increased incidence and mortality rate, and a threefold increased rate by age 77.

“It is notable that the threefold increase in risk of ovarian cancer by age 77 we observed for women with irregular/infrequent cycles in this study is equal to the increase in risk observed for women with a family history of ovarian cancer in a first-degree relative,” explained Cohn. “Our study finding could lead to better understanding of the 90 percent of ovarian cancers that occur in women with no family history of ovarian cancer and with no known high-risk inherited mutations.”

Between 1959 and 1967, CHDS enrolled more than 15,000 pregnant women in its study and followed them for more than 50 years to study factors impacting health during pregnancy. CHDS used medical records and self-reported data from these women at age 26 on their menstrual irregularity, including those whose cycles were longer than 35 days and those who had anovulation. The researchers used this information as a proxy for polycystic ovarian syndrome (PCOS).

Of these women, 13 percent reported menstrual irregularities. 116 were diagnosed with ovarian cancer, at around 63 years of age on average, and 84 of them died from the cancer.
 
The association between menstrual irregularities and ovarian cancer death was independent of age, race, parity and weight. The researchers ruled out use of fertility drugs or contraceptives prior to pregnancy as an explanation for their findings. Infertility was also ruled out, since all women in the study had achieved a live birth.

They also found that when the data were analyzed by ovarian cancer type, menstrual irregularities increased risk for death from serous-type cancers by threefold, regardless of age.

Findings from this study are contrary to the existing expectation that PCOS, which is characterized by less frequent ovulation and irregular or long menstrual cycles, would protect the ovary. However, infrequent ovulation is not the only hallmark of PCOS; there are a number of anatomical, hormonal and metabolic abnormalities associated with PCOS that might explain the study findings, said Cohn.

This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, an institute of the National Institutes of Health.

View the manuscript online.

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If you are interested in arranging an interview with Barbara A. Cohn, PhD, contact Jennifer Scroggins at (510) 285-5512 or jennifer.scroggins@phi.org