Women with irregular menstrual cycles are at two-fold increased risk of dying from ovarian cancer.
A new study conducted by researchers from the Child Health and Development Studies at the Public Health Institute (PHI) followed 14,403 pregnant women who had a single live birth between 1959 and 1967 for fifty years. During this period they monitored all factors that may impact health during pregnancy.
The researchers collected data on menstrual irregularity including cycles that were longer than 35 days and and ovulation. Thirteen percent of the study participants reported menstrual irregularities when they were about 26 years old. Of these, 64 women died from ovarian cancer by the time they were 69 years of age.
"Among reproductive cancers, ovarian cancer is the most common cause of death, because it is usually diagnosed late in the disease process after it has spread," said Barbara A. Cohn, author of the study, in a statement. "Unfortunately, there is no reliable method for early diagnosis or screening, and symptoms like abdominal pain and bloating often do not come to a woman's attention until the cancer has spread."
"It is notable that the 2.4-fold increase in risk of ovarian cancer death we observed for women with irregular/infrequent cycles in this study is close to the threefold 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."
Influencing factors like age, race, parity, and weight were taken into consideration during the study. Researchers also noted that the link between menstrual irregularities and ovarian cancer death was more prominent in women after they reached their mid-60s.
On further analysis of the type of ovarian cancer, researchers found that menstrual irregularities increased risk for serious-type cancers and endometrioid-type cancers by nearly threefold and fourfold, respectively. The incidence of late-stage ovarian cancer was also higher in women who experienced irregular or infrequent menstrual cycles.
Findings of the new study debunk current beliefs that polycystic ovarian syndrome (PCOS), characterized by irregular periods protects the ovary. The only good that comes out of less-frequent ovulation is that it can help women lose weight.
Researchers are yet to determine why irregular menstrual cycles might increase the risk of dying from ovarian cancer. Hormones may be a possible explanation. According to Cohn, the ovaries in these women may be exposed to lower amounts of the hormone progesterone, which is released after ovulation and may protect against ovarian cancer, Live Science reports.
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. Cohn declares no conflicts of interest.
