Birth Control Pills Linked to Breast Cancer. AgainFeb 25, 2009 | Parker Waichman LLP
A recent study has concluded that birth control pill use is linked with an increased risk of breast cancer, said Reuters, citing a report in the American Journal of Epidemiology.
Prior to this new report, the breast cancer-oral contraceptive link was, according to Dr. Lynn Rosenberg, from Boston University, and colleagues, based "largely on ... studies conducted before 1990," reported Reuters. The Denver Wellness Examiner pointed out that critics of these prior studies have long argued that the data is based on older medication and that there have been significant changes in dosing strength since the 1990s. Clearly, it noted, the critics have been proven wrong.
The researchers used information from the Case-Control Surveillance Study to look at birth control pill use and breast cancer risk in women diagnosed with breast cancer between 1993 and 2007, said Reuters. The study took also looked at race and tumor hormone receptors and involved over 2600 women; 907 with breast cancer and 1771 who did not suffer from breast cancer.
The team found that women who had taken oral contraceptives for at least one year experienced a 50 percent greater chance of developing breast cancer over women who took the pills for less time or who had never taken the pills, said Reuters. Also, greater duration, use in the past decade, and being of black ethnicity, all seemed to raise the incidence of breast cancer; however, the reason for those associations remains unclear. Hormone receptor status did not have an affect on the link. The team concluded that, "Given the widespread use of oral contraceptives, continued evaluation of their possible health effects may be warranted," quoted Rerters.
Estrogens, said the Denver Wellness Examiner, cause cells to multiply and divide, noting that the more a cell divides, the greater the chance for cancer to develop. The National Cancer Institute (NCI) explains that two types of oral contraceptives are available in the United States. One—a combined pill—contains two artificial versions of the natural female hormones estrogen and progesterone, similar to what the ovaries normally produce. The other—the minipill—only contains a type of progesterone.
Estrogen stimulates the growth and development of the uterus at puberty, causes the endometrium, or inner uterine lining, to thicken during the first half of the menstrual cycle, and affects breast tissue throughout a woman’s lifetime, specifically from puberty to menopause. Progesterone is produced during the last half of the menstrual cycle; prepares the endometrium to receive the egg; and if an egg is fertilized, continues producing to prevent further egg release. It is because of this that progesterone is called, said the NCI, the “pregnancy-supporting” hormone.
Studies suggest that some cancers depend on naturally occurring sex hormones for their development and growth, specifically cervical and breast cancers.
In 2003, an NCI-sponsored study examined risk factors for breast cancer among women ages 20 to 34 versus women ages 35 to 54 and looked at women diagnosed with breast cancer and women’s oral contraceptive use. The study found that breast cancer risk was highest in women who used oral contraceptives within five years prior to diagnosis, with women in the younger group being most susceptible.