Early oral contraceptive use as a prognostic factor in breast cancer.

The survival of 193 premenopausal breast cancer patients was investigated in relation to their history of early use of oral contraceptives. The women were born in 1939 or later and diagnosed in the southern health care region of Sweden. Women, who had started their oral contraceptive use (OC-use) before 20 years of age had a significantly lower survival rate as compared with those who had never used OC and late users (p = 0.02 and = 0.04 respectively, generalized Wilcoxon test). For women who started OC-use between 20 to 25 years of age, a tendency for a shorter survival was seen in comparison with women who had never used OC (p = 0.18). For all patients simultaneously, the relative risk adjusted for age at diagnosis increased for earlier OC-start. When only stages II and III were considered in a stratified multivariate model, a significantly elevated risk was seen for early users of OC irrespective of age or of adjuvant treatment given. The estrogen and progesterone receptor concentrations of the primary tumor were significantly lower among early users (p = 0.001 and p = 0.05 respectively).