Abstract
BACKGROUND: Postpartum diagnosis of breast cancer confers increased risk of metastasis and death, possibly because of protumorigenic pathways that occur after weaning. We sought to evaluate the impact of postpartum diagnosis on survival in patients with inflammatory breast cancer (IBC). METHODS: We performed a retrospective analysis of patients with nonmetastatic IBC enrolled in a prospective registry (2007-2023). Kruskal-Wallis, χ2, and Fisher exact tests were used to compare between postpartum groups. The Kaplan-Meier method and log-rank tests were used for survival estimates. RESULTS: Among 320 patients with IBC, 25 (7.8%) were nulliparous, 31 (9.7%) were 0 to 5 years postpartum, 26 (8.1%) were 6 to 10 years postpartum, 56 (17.5%) were 11 to 20 years postpartum, and 182 (56.9%) were >20 years postpartum. Groups were similar with respect to race/ethnicity, body mass index, grade, receptor subtype, stage, trimodality therapy receipt, and pathologic complete response rate. At a median follow-up of 77 months (95% confidence interval, 69.3-86.5), there were no significant differences in overall survival, progression-free survival, and locoregional and distant recurrence-free survival by postpartum status. On multivariable analysis, parity status and years postpartum were not significantly associated with survival outcomes after controlling for age, stage, and receptor subtype. CONCLUSIONS: In this cohort of patients with IBC with a high proportion of childbearing, postpartum diagnosis did not significantly affect survival outcomes. The aggressive biology of IBC may override any additional risks imposed by a postpartum diagnosis. IMPACT: Unlike in noninflammatory invasive breast cancer, postpartum diagnosis did not negatively affect prognosis in IBC. These findings highlight the continuing need to identify unique drivers of aggressive biology in IBC.