Impact of Timing of Diagnosis and Breastfeeding on Postpartum Breast Cancer Outcomes

Purpose Postpartum breast cancers (PPBC) have a worse prognosis than other breast cancers, but the impact of timing postpartum (PP) and concurrent breastfeeding (BF) remains unclear. Methods We analyzed 161 PPBC patients diagnosed from 2002–2014, hypothesizing that diagnosis < 2 years PP (vs 2–5 years) and concurrent BF (vs not BF) at diagnosis would be associated with inferior outcomes. We compared 2-year PP patients (N = 60) and 2–5 year PP patients (N = 101), and subsequently, patients who were (n = 36) and were not (n = 24) BF at diagnosis among the 2-year PP group with respect to diagnostic patterns and survival. Differences were evaluated using chi-square tests. Kaplan-Meier analysis assessed overall survival (OS) and distant disease-free survival (DDFS). Results Median follow-up was 54 months. Patients in the 2-year PP group were more likely to be BF at diagnosis (60% vs 7%, p < .001), diagnosed at a higher clinical T-stage (20% vs 50% T1, p < .001) and N-stage (37% vs 61% N0, p = .01), had worse 5-year OS (79% vs 97%, p < .001), and DDFS (74% vs 93%, p = .003) compared to 2–5 year PP patients. Among 2-year PP patients, patients BF at diagnosis were more likely to be diagnosed with mastitis preceding diagnosis (31% vs 4%, p = .03), more often had their symptoms attributed to lactational change (58% vs 4%), had significantly worse 5-year DDFS (62% vs 91%, p = .032), and trended toward worse OS (74% vs 86%, p = .08) compared to those not BF. Conclusions Our findings suggest that early PPBC and BF at diagnosis are associated with poor outcomes and diagnostic delay.