The impact of pregnancy on breast cancer outcomes in women ≤35 years

BACKGROUND: Some evidence suggests that women with pregnancy-associated breast cancers (PABC) have a worse outcome compared with historical controls. However, young age is a worse prognostic factor independently, and women with PABC tend to be young. The purpose of the current study was to compare locoregional recurrence (LRR), distant metastases (DM), and overall survival (OS) in young patients with PABC and non-PABC. METHODS: Data for 668 breast cancers in 652 patients aged ≤35 years were retrospectively reviewed. One hundred four breast cancers (15.6%) were pregnancy-associated; 51 cancers developed during pregnancy and 53 within 1 year after pregnancy. RESULTS: The median follow-up for all living patients was 114 months. Patients who developed PABC had more advanced T classification, N classification, and stage group (all P < .04) compared with patients with non-PABC. Patients with PABC had no statistically significant differences in 10-year rates of LRR (23.4% vs 19.2%; P = .47), DM (45.1% vs 38.9%; P = .40), or OS (64.6% vs 64.8%; P = .60) compared with patients with non-PABC. For those patients who developed breast cancer during pregnancy, any treatment intervention during pregnancy provided a trend toward improved OS compared with delaying evaluation and treatment until after delivery (78.7% vs 44.7%; P = .068). CONCLUSIONS: Young patients with PABC had no statistically significant differences in LRR, DM, or OS compared with those with non-PABC; however, pregnancy contributed to a delay in breast cancer diagnosis, evaluation, and treatment. Primary care and reproductive physicians should be aggressive in the workup of breast symptoms in the pregnant population to expedite diagnosis and allow multi- disciplinary treatment.