After years of debate in the gynecology community, British researchers announced last week that taking a contraceptive pill does not increase a woman's chance of developing cancer, and it in fact may reduce this risk if she did not take the pill for longer than eight years.
After studying the records of 46,000 women during the course of 36 years, researchers at Aberdeen University found that taking an oral contraceptive for up to eight years did not lead to an increased risk of cancer during a woman's lifetime.
However, the research suggested the risk of cancer was higher for women who took the pill more than eight years.
"That is really significant for a couple of reasons," said P.J. Mann, vice president of health services for the Planned Parenthood Association of Lubbock. "Because (the study) lasted 36 years, it covers the early pills that were thought to have extremely high doses of estrogen. Secondly, they had a control group that had never been exposed to estrogen from outside the body."
According to the British Medical Journal Web site, www.bmj.com, the main data set contained about 339,000 woman years of observation for "never users" - women who had never taken the pill - and about 744,000 woman years for "ever users" - women who had taken it.
Ever users had significantly lower rates of cancer in the bowels, rectum, uterine body, ovaries, tumors of unknown site and malignancies.
Their rates also were lower on gynecological cancers and cancers in general.
"What's interesting to me is that this seems to decrease the rates of all cancers, not just female ones," said Cornelia DeRiese, a clinical associate professor in Obstetrics and Gynecology at the Texas Tech Health Sciences Center.
This study is important to review because it sheds new light on an issue that has worried doctors for years, Mann said.
"Something that's been very worrisome to American doctors is the age-old question, 'Can birth control put you at a greater risk for cancer?'" she said. "This says that in some cases it can actually cut the risk by up to 12 percent."
According to the study, that 12 percent reduction is equal to one fewer case of cancer for every 2,200 women who used the pill for a year.
"The thing that's important to remember, though, is that birth control usage is not an isolated factor," Mann said. "Lifestyle and genetics also contribute to a person's risk of getting cancer."
One of the benefits of this study is the number of women involved, DeRiese said.
"They're using a big number of patients," she said. "Generally speaking, the larger the number of patients, the better the interpretation is going to be."
Mann said she agreed the numbers were among the study's strongest points, but she leaned more from the length of time rather than the number of subjects.
"The numbers alone are significant in this study," Mann said. "If there's a study that lasts four to five, even up to 10 years, you still don't see the negative outcomes in that time period."
Mann said the study also is meaningful because it is longitudinal - it followed the same people over a period of time.
The last research to come out linking pill usage and cancer was almost 10 years ago, DeRiese said. That information showed conflicting results on the types of cancers affected by the pill.
"Suppressing ovulation reduces the risk of ovarian cancer," she said, explaining the previous research. "It's close to a 50 percent reduction, but it may potentially increase the risk of breast cancer."
Mann said while the research is beneficial to both doctors and patients, she does not think it will affect the number of women who choose to use the contraceptive pill.
"I don't think this will significantly affect the way we prescribe birth control," she said. "I don't think it will significantly impact the consumer, either. This really just provides reassurance."
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