Recent research at the Medical Center indicates that women who take oral contraceptives containing higher levels of the hormone progestin may reduce their risk of ovarian cancer.
"Previously, the only women who could benefit from taking preventative drugs short of doing an operation were those who were young and still ovulating," said study co-author Dr. Gustavo Rodriguez, an adjunct professor of oncology at Duke.
"We now have a great opportunity to develop a treatment that will lower the risk of ovarian cancer for women of all ages."
Co-author Dr. Joellen Schildkraut, associate professor in the department of community and family medicine, studied data from 390 women who were diagnosed with ovarian cancer and classified each woman's oral contraceptive regimen by its estrogen- and progestin-potencies.
The study, published earlier this month in the Journal of the National Cancer Institute, reports that oral contraceptives with high-potency progestin taken for three or more years were twice as protective against the development of ovarian cancer compared to low-potency formulations taken during the same time period. The amount of estrogen did not seem to affect this risk.
Oral contraceptives have commonly been used in the past to prevent ovarian cancer because they suppress ovulation and modify the hormonal environment of the ovary. However, these findings suggest not only that progestin plays a large role in the regulation of cancerous cells, but also that its level is significant.
However, Schildkraut cautions that the study has some limitations.
"This was a retrospective study, so it is possible people reported incorrect information about their oral contraceptive usage," she said.
It is also unclear if progestin has the same preventative effect on other cancer types, and there is concern that progestin increases the risk of breast cancer.
In previous experimental studies, scientists found that progestin has a role in triggering apoptosis, or cell death. Apoptosis is the normal regulatory mechanism that the body uses to cleanse the ovarian surface of damaged cells.
In addition, the researchers have identified a potential mediator molecule called transforming growth factor beta, which is a known tumor suppresser that each cell naturally produces.
"[Observation of activated TGF beta in response to progestin] may indicate that there is more than one mechanism at work here," said Rodriguez, who recently left Duke to become an adjunct associate professor with Northwestern University's medical school.
Ongoing and future research includes identifying the pathways by which progestin produces its protective effects. Furthermore, researchers are considering agents other than progestin, such as vitamin D, that have shown great promise in reducing ovarian cancer risk.
However, the researchers believe these findings are a step in the right direction. "This opens the door towards developing a new broad approach that can be used by all ages to prevent ovarian cancer in the future," Rodriguez said.
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