Oral Contraceptives Cut Ovarian Cancer Risk
FRIDAY Jan. 25, 2008 -- Woman who take oral contraceptives greatly reduce their risk of developing ovarian cancer, and the longer they take them the greater the protection, a new study confirms.
The use of oral contraceptives has long been connected with reductions in the incidence of ovarian cancer. The authors of the new study say their findings show that the Pill has already prevented 200,000 ovarian cancers and 100,000 deaths worldwide. Over the coming decades, use of the Pill will prevent some 30,000 cases of ovarian cancer each year, they contend.
"What's new here is that we have brought together all the people who have done epidemiological studies on ovarian cancer," said study co-author Dr. Valerie Beral, of Oxford University's Cancer Research UK Epidemiology Unit, in England. "This is pretty much what we know today."
"If women take the Pill, [ovarian] cancer is not their worry," Beral added.
For the study, Beral's team -- the Collaborative Group on Epidemiological Studies of Ovarian Cancer -- analyzed the results of 45 studies of ovarian cancer. These studies included 23,257 women with the disease and 87,303 women who did not have the disease. Thirty-one percent of those with ovarian cancer had used oral contraceptives, compared with 37 percent of the women who did not have cancer.
The researchers found that women who took oral contraceptives for 10 years reduced their risk of ovarian cancer from 12 per 1,000 women to eight per 1,000, and death from the disease from seven per 1,000 women to five per 1,000. They also found that this protective effect can last for decades after a woman stops using the Pill.
The findings are published in the Jan. 26 issue of The Lancet.
The protection from ovarian cancer is greater than the risk of other cancers associated with use of the Pill, such as breast and cervical malignancies, Beral said.
"There is a slight transient risk of breast cancer and cervical cancer, but that goes away when you stop taking the Pill," she said. "But the decrease in ovarian cancer is persistent and long-lasting. The magnitude of this outweighs the other risk."
Beral doesn't think women should decide whether to take the Pill based on its ability to reduce ovarian cancer risk. "The decision to take the Pill is about contraception, but there is a bonus at the end of all that," she said.
Dr. Eduardo Franco, a professor of epidemiology and oncology at McGill University in Montreal, and co-author of an accompanying editorial in the journal, said this study answers a lot of lingering questions about the extent of the protection the Pill offers against ovarian cancer.
"Oral contraceptives are beneficial to women worldwide," Franco said. "In fact, a lot of ovarian cancers have been averted."
Franco noted that estrogen in oral contraceptives has a protective effect, yet after menopause hormone-replacement therapy is associated with an increased cancer risk. "What is protective before menopause gets to be harmful after menopause," he said. "It's an exercise in risk and benefit."
Another editorial in the same journal issue argues for making oral contraceptives available over-the-counter. "We believe that the case is now convincing. Women deserve the choice to obtain oral contraceptives over-the-counter, removing a huge and unnecessary barrier to a potentially powerful cancer-preventing agent," the journal editorial states.
"A strong message about the overall cancer-preventing benefits of oral contraceptives would be a positive public health message, empowering women to decide for themselves about the evidence," the editorial concludes.
However, Franco strongly disagrees with this proposal. "Because of the complexity of use and the potential for misuse, it should always be a prescription medication," he said.
According to the American Cancer Society, ovarian cancer is the eighth most common cancer in women, skin cancer excluded. It's the fifth-leading cause of cancer death in women. An estimated 22,430 new cases of ovarian cancer are diagnosed in the United States each year, and about 15,280 women die from the disease. Two-thirds of women with ovarian cancer are 55 or older.
To learn more about ovarian cancer, visit the U.S. National Cancer Institute.
Posted: January 2008