July 9 (HealthDay News) -- Among women with ovarian cancer, those who had their first menstrual period before the age of 12 and who had the most menstrual cycles over a lifetime are more likely to die of the cancer than those who had fewer ovulatory cycles, a new study shows.
U.S. researchers analyzed data on 410 women, aged 20 to 54, who had ovarian cancer and were enrolled in the Cancer and Steroid Hormone (CASH) study between 1980 and 1982.
Using data that included in-depth patient interviews, reproductive history, contraceptive use and personal and family medical history, the researchers divided the women into groups based on their total number of ovulatory cycles.
There were 212 deaths among the participants during a median follow-up of 9.2 years, the study authors noted.
Women in the group who had the highest number of lifetime ovulatory cycles had a 67 percent greater chance of dying during the study follow-up, which ranged up to about 17 years.
The findings were independent of a woman's age at the time of the study, which would of course have a significant impact on the number of menstrual cycles a woman had had, said study author Cheryl Robbins, an epidemiologist at the U.S. Centers for Disease Control and Prevention.
Ovarian cancer patients whose age at menarche, or first menstrual cycle, was younger than 12 were 51 percent more likely to die from the cancer than those whose age at menarche was 14 or older, according to the study, published in the July issue of Cancer Epidemiology, Biomarkers & Prevention.
Ovarian cancer is the fifth-leading cause of cancer deaths among women. The high mortality is due, in part, because the disease is typically discovered after it has spread. Only about one-fifth of ovarian cancers are detected when the cancer is still localized, the study authors noted.
Previous research has linked age at first menstrual period and number of lifetime menstrual cycles with the risk of ovarian cancer, while use of oral contraceptives and hysterectomy or tubal ligation, which halt ovulation, have also been shown to reduce the risk of developing ovarian cancer.
Other studies have also found that having children earlier in life, having multiple children and breast-feeding provide protection, but the results are inconsistent, the researchers noted.
But less is known about the impact of those hormonal and reproductive factors on survival rates for women who already have the cancer.
"Although we have relatively good knowledge about the influence of reproductive factors on the risk of developing ovarian cancer, knowledge is rather limited regarding the reproductive factors that may influence survival after diagnosis with this serious disease," Robbins said.
Though the exact mechanism isn't understood, researchers believe that the surge of hormones brought on by ovulation, or the insult to the cells that occurs during ovulation, may be associated with more aggressive tumors, Robbins said.
In the current study, while age at first period and total lifetime menstrual cycles impacted survival, other factors, including number of pregnancies, breast-feeding and menopausal status did not show a statistically significant impact on survival rates.
Dr. Mary B. Daly, director of the Personalized Cancer Risk Assessment Program at the Fox Chase Cancer Center in Philadelphia, said the results shed more light on the role reproductive hormones play in ovarian cancer, potentially providing clues for developing new treatments for aggressive cancers.
Yet the study has its limitations, Daly added. Women's recollections could have been flawed, and the study participants were younger than the typical ovarian cancer patient and so may not be truly representative. Additionally, the women in the study had ovarian cancer nearly 30 years ago and would not have been receiving today's more advanced chemotherapy treatments.
Nor is the research definitive enough to suggest that women should go out and start taking contraceptive pills or having babies earlier to increase their chances of surviving ovarian cancer.
"The paper may suggest other avenues of research into what is it about the hormonal profile of women that could affect the biology of their ovarian cancer," Daly said. "As of right now, it doesn't translate into something you could clinically do differently."
SOURCES: Cheryl L. Robbins, Ph.D., epidemiologist, U.S. Centers for Disease Control and Prevention, Atlanta; Mary B. Daly, M.D., Ph.D., director, Personalized Cancer Risk Assessment Program, Fox Chase Cancer Center, Philadelphia; July 2009 Cancer Epidemiology, Biomarkers & Prevention