Ovarian cancer risk lower with longer time on Pill
For each year that a woman takes an oral contraceptive, her risk of ovarian cancer is reduced by about 5 percent on average, report investigators from the University of Hawaii.
The reduction in ovarian cancer risk becomes apparent after a short time since first use (five years or less) and a short duration of use (one year), note Dr. Galina Lurie and colleagues.
Lurie, with the Cancer Research Center of Hawaii at the University of Hawaii in Honolulu, and her colleagues identified these protective effects after studying data on 813 women with epithelial ovarian cancer and 992 women without ovarian cancer.
The women all resided in Hawaii or Los Angeles, California between 1993 and 2006, the investigators report in the journal Epidemiology.
Women who used oral contraceptives for approximately one year showed a reduced ovarian cancer risk, but only if they had stopped oral contraceptive use less than 20 years previously.
“Protection against ovarian cancer was not significant in women who used oral contraceptives only for a short period of time (less than 1 year) during their teenage years,” Lurie told Reuters Health.
On the other hand, “Among women who used oral contraceptives for more than one year, the protective effect lasted 2 to 3 decades after cessation of use,” Lurie noted.
The protective effects seen were independent of oral contraceptive potency, the number of pregnancies, or the woman’s age at first or last full-term or incomplete pregnancy, Lurie said.
The results show that in addition to duration of use, time since first and last use of oral contraceptives is an important factor to consider when examining the association between oral contraceptives and the risk of ovarian malignancy, Lurie commented.
The mechanism for the protective influence of oral contraceptives against epithelial ovarian cancer remains unclear, the investigators note. Therefore, additional studies should further investigate the risks and benefits of low-dose oral contraceptives for women’s health, Lurie said.
SOURCE: Epidemiology, March 2008
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