Does pregnancy-associated breast cancer imply a worse prognosis? A matched case-case study.

BACKGROUND Significant controversy exists in the literature regarding the role of pregnancy in the prognosis of breast cancer. We designed a matched case-case study, matching pregnancy-associated breast cancer (PABC) cases with breast cancer cases for stage, age, and year of diagnosis. PATIENTS AND METHODS 39 consecutive cases of PABC were matched with 39 premenopausal cases of breast cancer. Univariate and multivariate survival analyses followed by adjustment for stage, grade, estrogen receptor status, and age at diagnosis, were performed. RESULTS Regarding overall survival (OS), univariate analysis pointed to longer OS in non-PABC cases vs. PABC cases. Accordingly, a more advanced stage predicted shorter survival. In the multivariate analysis, the independent aggravating effect mediated by pregnancy persisted. Interestingly, a post hoc nested analysis within PABC cases indicated that the 3rd trimester pointed to shorter OS. The aforementioned results on OS were also replicated during the examination of relapse-free survival. CONCLUSION Implementing a matched case-case design, the present study points to pregnancy as a poor prognostic factor for breast cancer.