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Depo-Provera and Norplant Do Not Increase Breast Cancer Risk

In the Women's Contraceptive and Reproductive Experiences (CARE) study -- a population-based, multicenter, case-control study supported by the National Institute of Child Health and Human Development and the CDC -- 4575 randomly sampled black and white women (age range, 35-64) with primary invasive breast cancer diagnosed between 1994 and 1998 were compared with 4682 age- and race-matched controls. The researchers ascertained previous use of the injectable contraceptive depot medroxyprogesterone acetate (DMPA; Depo-Provera) and the levonorgestrel-releasing contraceptive implant (Norplant; not currently marketed in the U.S.).

Overall, 127 participants (58 cases and 69 controls) had used DMPA, and 12 (5 cases and 7 controls) had used the implant. No significant increase or decrease in breast cancer risk was associated with exposure to DMPA or the implant. In subanalyses for DMPA use, risk did not vary significantly by age, menopausal status, recency or duration of use, or age at first use.

Comment: Findings from the estrogen-progestin arm of the Women's Health Initiative hormone therapy study have heightened concerns that hormonal contraceptive use might increase breast cancer risk. Earlier findings from the Women's CARE study (Journal Watch Women's Health Aug 20 2002) reassured clinicians and their patients that oral contraceptives do not increase breast cancer risk. The current findings provide reassurance that progestin-only injectable and implantable contraceptives also are safe with respect to breast cancer risk. Although the six-implant system (Norplant) is not currently marketed in the U.S., a single-implant contraceptive (Implanon) might become available here within the year. Because of its effectiveness and convenience, DMPA currently is used by one to two million U.S. women. Accordingly, the current findings from the Women's CARE study are welcome indeed.

— Andrew M. Kaunitz, MD

Published in Journal Watch Women's Health June 22, 2004

Citation(s):

Strom BL et al. Absence of an effect of injectable and implantable progestin-only contraceptives on subsequent risk of breast cancer. Contraception 2004 May; 69:353-60.

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