Risk of Breast Cancer in Relation to the Use of Injectable Progestogen Contraceptives and Combined Estrogen/Progestogen Contraceptives

• Published in: American journal of epidemiology Vol. 151; no. 4; pp. 396 - 403
• Main Authors: Shapiro, Samuel, Rosenberg, Lynn, Hoffman, Margaret, Truter, Hanneke, Cooper, Diane, Rao, Sowmya, Dent, David, Gudgeon, Anne, Zyl, Jakobus van, Katzenellenbogen, Judith, Bailie, Ross
• Format: Journal Article
• Language: English
• Published: Cary, NC Oxford University Press 15.02.2000
• Subjects: Adult; African Americans - statistics & numerical data; African Continental Ancestry Group; Biological and medical sciences; breast neoplasms; Breast Neoplasms - chemically induced; Breast Neoplasms - epidemiology; Case-Control Studies; contraceptives; Contraceptives, Oral, Combined - adverse effects; Female; Gynecology. Andrology. Obstetrics; hormonal; Humans; Injections, Intramuscular; Mammary gland diseases; Medical sciences; Medroxyprogesterone Acetate - administration & dosage; Medroxyprogesterone Acetate - adverse effects; Middle Aged; oral; Progesterone Congeners - administration & dosage; Progesterone Congeners - adverse effects; Risk Factors; South Africa - epidemiology; Tropical medicine; Tumors; South Africa(Republic); Africa; South Africa; Human; Mammary gland diseases; Estroprogestagen; Risk factor; Oral administration; Contraception; Case control study; Mammary gland; Malignant tumor; Epidemiology
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/oxfordjournals.aje.a010219

Recent studies have suggested that progestogen-only contraceptives and combined estrogen/progestogen oral contraceptives (COCs) may increase the risk of breast cancer among women less than 35 years of age or among recent users, The authors conducted a case-control study, in which cases of breast cancer (n = 419) and controls (n = 1,625) hospitalized for conditions unrelated to contraceptive use were interviewed from 1994 to 1997 in hospitals in greater Cape Town, South Africa. The women were aged 20–54 years, resided in a defined area around Cape Town, and were Black or of mixed racial descent. The relative risk for exposure to injectable progestogen contraceptives (IPCs), mostly depot medroxyprogesterone acetate, was 0.9 (95% confidence interval (CI) 0.7, 1.2). There were no consistent associations within categories of age or recency or duration of use. For exposure to COCs, the overall relative risk was 1.2 (95% CI 1.0, 1.5). Among women below age 35 years, the relative risk was 1.7 (95% CI 1.0, 3.0), and it was unrelated to the duration or recency of use. The findings suggest that IPCs do not increase the risk of breast cancer, and that COCs may increase the risk among women below age 35 years, although bias cannot be excluded. Am J Epidemiol 2000;151:396–403.