The more than 10 million women who use oral contraceptives face a quandary. When taken for six years or more, the pill can lower the incidence of ovarian cancer by 50%. But the risk of breast and cervical cancer rises some. Researchers at the University of Southern California's School of Medicine are designing a contraceptive that may prevent these cancers.
The pill contains synthetic versions of the hormones estrogen and progesterone. The levels of these must be high enough to prevent ovulation. When ovulation stops, these same hormones prevent such postmenopausal symptoms as osteoporosis and hot flashes. Malcolm C. Pike, chairman of preventive medicine at USC's medical school, says the dosage necessary to avoid such symptoms is about 60% lower than that needed to prevent ovulation. And it is high levels of the hormones that seem to stimulate breast cancer.
Pike's new regimen uses a brain compound called GnRHA that also prevents ovulation and reduces ovarian cancer. He then gives women just enough estrogen and progesterone to prevent postmenopausal symptoms. These low levels reduce the risk of breast cancer, says Pike. Some 14 women at risk of breast cancer have safely taken the regimen, which must be injected monthly. Pike is talking to investors about funding larger tests of a regimen taken every four months.