Risk of invasive cancer of the cervix in relation to the use of injectable progestogen contraceptives and combined estrogen/progestogen oral contraceptives (South Africa).

BACKGROUND: Cervical cancer is caused by specific types of the human papilloma virus (HPV), but not all infected women develop cancer. It has been hypothesized that hormonal contraceptives may potentiate the oncogenicity of HPV infection.

METHODS: In a case-control study of colored and black women in the Western Cape Province, South Africa, 524 incident cases of clinically evident invasive cervical cancer (stages 1b-1V) were compared with 1541 controls, and with a subgroup of 254 HPV-positive controls.

FINDINGS: For injectable progestogen contraceptives (95% of which were depot medroxyprogesterone acetate) the overall relative risk, adjusted for confounding, was 1.0 (95% confidence interval 0.8-1.3); for combined estrogen/progestogen oral contraceptives the corresponding estimate was 0.8 (0.7-1.1). When the data were divided into categories of duration of use extending to > or = 15 years, or according to age, ethnic group, or recency of use, there was no consistent evidence of an increased risk. The findings were unchanged when the cases were compared with the HPV-positive controls.

INTERPRETATION: The present findings suggest that neither injectable progestogen-only nor combined estrogen/ progestogen oral contraceptives increase the risk of clinically evident invasive cancer of the cervix.