Absence of an effect of injectable and implantable progestin-only contraceptives on subsequent risk of breast cancer

Animal data indicate that both estrogens and progestins could be carcinogenic and that progestins could serve as tumor promoters. Human studies have not confir/B an increased risk of breast cancer from long-term use of oral contraceptives, but have shown an increased risk from hormone replacement th...

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Bibliographic Details
Published in:Contraception (Stoneham) 2004-05, Vol.69 (5), p.353-360
Main Authors: Strom, Brian L., Berlin, Jesse A., Weber, Anita L., Norman, Sandra A., Bernstein, Leslie, Burkman, Ronald T., Daling, Janet R., Deapen, Dennis, Folger, Suzanne G., Malone, Kathleen E., Marchbanks, Polly A., Simon, Michael S., Ursin, Giske, Weiss, Linda K., Spirtas, Robert
Format: Article
Language:English
Subjects:
Absorbable Implants
Adult
Biological and medical sciences
Breast cancer
Breast Neoplasms - chemically induced
Breast Neoplasms - epidemiology
Broxyprogesterone acetate
Case-Control Studies
Contraceptive patch
Contraceptives
Drug toxicity and drugs side effects treatment
Female
Humans
Implantable contraceptives
Injectable contraceptives
Injections, Intramuscular
Medical sciences
Middle Aged
Pharmacology. Drug treatments
Progestin
Progestins - administration & dosage
Progestins - adverse effects
Toxicity: urogenital system
United States - epidemiology
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Summary:Animal data indicate that both estrogens and progestins could be carcinogenic and that progestins could serve as tumor promoters. Human studies have not confir/B an increased risk of breast cancer from long-term use of oral contraceptives, but have shown an increased risk from hormone replacement therapy including progestins. The present study analyzed the relationship between breast cancer and use of injectable and implantable progestin-only contraceptives. Analyses were perfor/B on data collected in a population-based, multicenter, case-control study, the Women's Contraceptive and Reproductive Experiences Study of the National Institute of Child Health and Human Development. The study involved 4575 randomly sampled cases with invasive breast cancer diagnosed between 1994 and 1998, and 4682 controls, identified using random digit dialing. We assessed the association between exposure to injectable contraceptives and risk of breast cancer. The use of injectable contraceptives was not associated with an increased risk of breast cancer [odds ratio (OR) = 0.9, 95% confidence interval (CI): 0.7, 1.2]. Risk was not increased among current users, defined as women who used injectable contraceptives within 1 year of the reference date (OR = 0.7, 95% CI: 0.4, 1.3) or those who initiated use in the 5 years im/Biately preceding the reference date (OR = 0.9, 95% CI: 0.5, 1.4), or with use beginning before age 35 (OR = 0.9, 95% CI: 0.6, 1.3). Among users, risk increased with increasing duration of use (p = 0.03). However, short-term users (
ISSN:0010-7824
1879-0518
DOI:10.1016/j.contraception.2003.12.015