Birth Control Pill and Cancer Prevention

Recent studies indicate that the birth control pill may be responsible for a decrease in the rates of certain cancers in Baby Boomer women. The Baby Boom refers to the sudden large increase in the birthrate, especially in the United States, from the latter half of the 1940s through the early 1960s. Women who started taking birth control pills in the 1960s are getting less ovarian and endometrial cancers, forms of cancer which typically show up in women over 50. "Starting this year, the incidence of ovarian cancer in the United States is expected to drop by 30 percent," said Harriet Smith of the University of New Mexico School of Medicine in Albuquerque.

The birth control pill, sometimes known simply as the Pill, was introduced to the public in the 1960s as an oral contraceptive, meaning that it would prevent pregnancy if taken by mouth. The synthetic hormones estrogen and progesterone in birth control pills prevent women from ovulating, or releasing eggs every month, and trick the body into believing that it is already pregnant. Without ovulation there is no way for sperm to fertilize an egg and produce a pregnancy. Estrogen is a hormone secreted by the ovaries that is responsible for development and maintenance of typical female sexual characteristics. The ovaries also produce progesterone, which prepares the uterus for, and maintains it during, pregnancy.

Ovarian cancer is the leading reproductive-system cancer in American women. Each year, 23,000 new cases a year are diagnosed and 14,000 women die of the disease. The disease affects a woman's ovaries, the pair of reproductive organs that produce ova, or eggs. The overall risk of contracting ovarian cancer is 1.8%, but for women 30 to 50 years old, only about 20 per 100,000 will get it. For women between the ages of 50 and 75, the annual incidence of the disease increases to 40 out of every 100,000 women. The disease typically strikes women after menopause, the natural and permanent end to menstruation that usually occurs between the ages of 45 and 55.

The risk of ovarian cancer is linked to the number of years of ovulation. The more years a woman ovulates, the higher her risk for ovarian cancer. Women who ovulate fewer times are less likely to develop the cancer. Reasons for fewer ovulations include multiple pregnancies, taking birth control pills, and breast-feeding, which tends to suppress ovulation so that the mother's body is not doubly taxed by providing milk for an infant and providing for pregnancy. According to Dr. Luis Padilla-Paz, also from the University of New Mexico, regular use of birth control pills reduces the risk of ovarian cancer by 30% to 50%.

The reason birth control pills reduce the incidence of this cancer is that they contain the hormones estrogen and progesterone. Researchers believe that the progesterone accounts for the anti-cancer impact of the pill. Estrogen, which is used to treat some symptoms of menopause, may actually cause some kinds of cancer. According to Dr. Smith, the protective effect of birth control pills can last several years after a woman has stopped taking them.

There is also evidence that the incidence of endometrial cancer is reduced by taking birth control pills. The endometrium is the mucous membrane that lines the uterus. It swells every month in preparation for a possible pregnancy, so as to protect the fetus as it grows. When women menstruate, or expel an unfertilized egg-meaning they have not gotten pregnant-they shed this layer. The risk of endometrial cancer is reduced by 50% during the first year of use and is reduced by 11% for each year of additional use, according to Padilla-Paz. Hormone replacement therapy after menopause can also reduce the risk of endometrial cancer, perhaps by as much as 70%, according to some studies.

Sources

"The Pill Seen Cutting Baby Boomer Cancer Rates." (www.nlm.nih.gov/ medlineplus/ news/ fullstory_7513.html) A brief article describing the effects of birth control pills on cancer rates.