Breast cancer during pregnancy: results of maternal and perinatal outcomes in a single institution and systematic review of the literature.

To compare the maternal and the perinatal variables of the patients with pregnancy associated breast cancer (PABC) and the pregnant patients without breast cancer (PNABC), we retrospectively included 13 PABC cases and 66.265 PNABC patients. The PABC patients presented a lower mean gestational age at their delivery and had higher induction of labour and prematurity rates. A diagnosis was performed before stage III in 77% of the cases. The overall survival was 90%; moreover, we collected 16 manuscripts when gathering data from 1581 patients with PABC. The mean follow-up time was 70 ± 8 months. The mean maternal age at diagnosis was 34 years old. Most of the patients were at their second trimester of pregnancy. The gestational age at delivery was 35 weeks. A mastectomy was the most frequently used surgical approach. PABC should be managed by a multidisciplinary team, ensuring there is a rigorous oncological treatment, with foetal well-being. IMPACT STATEMENT What is already known on this subject? The malignant breast tumours diagnosed during pregnancy, or 1 year after a delivery are increasing, there is evidence supporting the treatment during a pregnancy with maternal and foetal safety. A PABC should be managed by a multidisciplinary team in a referral centre, ensuring that there is a rigorous oncological treatment with foetal well-being. What do the results of this study add? Our results show that the PABC patients in our centre had a mean maternal age older than the PNABC women, as well as a higher percentage of the induction of labour and prematurity. 48 Cancer was usually diagnosed in early stages, and the most common type was ductal infiltrating, with positive hormonal receptors. For those patients continuing their pregnancies, a mastectomy plus a lymphadenectomy was the most frequent chemotherapy, and was usually administered in the third trimester of pregnancy. What are the implications of these findings for future clinical practice and/or further research? Moreover, the number of publications concerning PABC has grown, series are still scarce. We understand the limitations of the low number of the cases on our population, but this study is the first which compare the PABC with the PNABC patients, allowing to describe and compare the obstetrical and perinatal variables. Finally, we consider it is of a paramount importance to create an international database to register in a prospective way all of the cases of PABC to increase our knowledge in this field.