Oral Contraceptives & the risk of Cancer

The International Agency for Research on Cancer, the Lyon-based cancer research agency of the World Health Organization, in its press release of the 29th of July 2005, informed of the publication of a monograph on the possible carcinogenicity [of] combined estrogen-progestogen oral contraceptives and combined estrogen-progestogen menopausal therapy, based on the conclusions of an international ad hoc working group of 21 scientists from 8 countries.

Previously, combined oral contraceptives had been determined to be carcinogenic to humans, but only primary liver cancer was specifically implicated. The Working Group, after a thorough review of the published scientific evidence, concluded that combined oral contraceptives alter the risk of several common cancers in women.

Estrogen-progestogen oral contraceptives were classified in the Group 1 of carcinogenic agents. This category is used when there is sufficient evidence of carcinogenicity in humans.

These conclusions are of enormous public health importance, since it is estimated that worldwide, more than 100 million women -- about 10% of all women of reproductive age -- currently use combined hormonal contraceptives. In addition, there has been widespread use of hormonal menopausal therapy: approximately 20 million women in developed countries.

For all these women, the message is that the use of oral contraceptives increases the risk of breast, cervix and liver cancer. On the contrary, the risks of endometrial and ovarian cancer are decreased in women who used combined oral contraceptives.

Regarding combined estrogen-progestogen menopausal therapy, WHO warns that it increases the risk of breast cancer and endometrial cancer (at least when progestogens are taken fewer than 10 days per month) and that there is not sufficient evidence to conclude that hormonal therapy has a protective effect at any cancer site.

The WHO experts call to a rigorous analysis to demonstrate what can be, at the end, the overall net public health outcome of the use of oral contraceptives. In addition, each woman who uses these products is now invited by WHO to discuss the overall risks and benefits with her doctor, taking into consideration her personal circumstances and family history of cancer and other diseases.

FIAMC invites all health care providers to attentively consider the results of the WHO study, which sheds new light on the prophetical value of Paul VI's "Humanae Vitae" and of John Paul II's "Evangelium Vitae" encyclicals, and encourages Catholic doctors to spread the methods for natural family planning also in Western affluent societies.

Gian Luigi Gigli, MD
President FIAMC