This headline comes from a July 29, 2005 Associated Press story reporting from London that the United Nations' International Agency for Research on Cancer has added hormone pills to the list of substances that can cause cancer. The article noted that hormonal menopause therapy was being reclassified from "possibly carcinogenic" to "carcinogenic" because of the consistent evidence from studies in recent years.
World Health Organization's cancer agency is widely regarded as the international authority on cancer-causing agents. The agency made the declaration after several recent high-profile studies linking combination hormone replacement therapy, (or HRT), to breast cancer.
A panel of 21 scientists conducted the analysis and concluded that estrogen and progestin therapy for menopause slightly increases the risk of endometrial cancer when progestin is taken fewer than 10 days a month. One study used in the U.N. agency's analysis showed the chance of a woman developing breast cancer during her lifetime rises from 1 in 7 in the general population to 1 in 6 with long term use of hormones.
The UN's cancer research agency also concluded that a common type of birth control pill, taken by about 10 percent of women of reproductive age, increases the risk of more types of cancer than previously thought. Previously the agency had determined that the birth control pill combining estrogen and progestin can cause liver cancer. Now, because of further research, the agency has determined that these pills also slightly increase the risk of breast and cervical cancer.
Vincent Cogliano, head of the UN's agency that evaluates the cancer risk of chemicals stated, "It's a complicated picture. There are still other reasons to take it. Each woman has to discuss it with her doctor and weigh the risks and benefits."