Oral contraceptives (OCs) are associated with a small increase in premenopausal breast cancer risk, especially in parous women who use them for 4 or more years before a first full-term pregnancy, according to a new meta-analysis.

Chris Kahlenborn, MD, of Altoona Hospital in Altoona, Pa., and colleagues conducted a meta-analysis of 34 studies conducted since 1980. The researchers found that OCs were associated with a slightly increased risk of breast cancer in general (OR, 1.19). In studies that provided separate data for parous and nulliparous women who used OCs, they found OR of 1.29 and 1.24, respectively. The risk was highest in parous women who used OCs for at least 4 years before a first full-term pregnancy (OR, 1.52).

“Although oral contraceptives appear to be carcinogenic, the relative risk is small and the absolute risk (excess breast cancers due to OC exposure) is very small,” stated the author of an accompanying editorial.

“From the perspective of epidemiology and public health, we must continue to closely follow the epidemiology of OC use and health outcomes, given the widespread use of these agents and their high potential to impact women’s health in both a beneficial and deleterious manner. The current study highlights the need for a close evaluation of OC use before first full-term pregnancy…”

Kahlenborn C, Modugno F, Potter DM, et al. Oral contraceptive use as a risk factor for premenopausal breast cancer: a meta-analysis. Mayo Clin Proc. 2006;81:1290-1302.

Source: Contemporary OB/GYN