INFLUENCE OF PREGNANCY ON THE OUTCOME OF BREAST-CANCER - A CASE-CONTROL STUDY

The relationship between pregnancy and the outcome of breast cancer re mains controversial. The purpose of this study was to determine the pr ognostic value of pregnancy at the time of diagnosis of primary infilt rating breast cancer. In a retrospective multi-center study we compare d a group of 154 patients presenting pregnancy-associated (PA) breast cancer with a control group of 308 patients presenting non-pregnancy-a ssociated (non-PA) breast cancer, Classic prognostic factors, treatmen t modalities, disease-free survival and overall survival were compared in the 2 groups. The relative importance of pregnancy was assessed by Cox multivariate analysis. There was a significantly higher proportio n of inflammatory breast cancer, large tumors and negative receptor st atus in the PA group. Five-year recurrence-free survival, metastasis-f ree survival and overall survival were lower both in the whole PA grou p and in the PA sub-group excluding patients with inflammatory breast cancer than in the corresponding non PA groups. According to clinical stage, histoprognostic grade and microscopic lymph-node involvement, p robability of 5-year metastasis-free survival and overall survival was lower in the PA group. Outcome was significantly poorer after chemoth erapy for patients in the PA sub-group than in the non-PA sub-group. M ultivariate analysis demonstrated that pregnancy was an independent an d significant prognostic factor. Pregnancy has an adverse effect on th e outcome of breast cancer. Concurrent or recent pregnancy should be t aken into account in the development of new systemic therapies. Our fi ndings have important implications for further research into the basic mechanisms of cancer. (C) 1997 Wiley-Liss, Inc.