[Does previous exposure to oral contraceptives modify survival in breast cancer?].

The influence of a positive history of oral contraceptive (OC) use on survival of breast cancer was studied in 471 patients. 297 (63%) of them were ever users of OCs and 202 (43%) were long-term users (> or = 49 months). The median follow-up amounted to 56 (6-96) months. Except for a significantly higher frequency of poorly differentiated tumours in OC users (p = 0.01) there was no difference in the distribution of histopathological features between OC users and non-users. Nevertheless, compared to non-users OC user showed a significantly increased 5-year-survival (p = 0.017). This effect was strongly correlated with duration of use (p = 0.004) and time since last use (p = 0.02). The influence of OC use achieved significance after a duration of use of four or more years or in case of OC use at the time of diagnosis. The positive effect persisted in multivariate analyses and was mainly attributed to long-term OC users with tumours of a generally expected poor prognosis.