Factors associated with improved outcomes for metastatic inflammatory breast cancer patients.

PURPOSE: Controversy exists regarding the role of locoregional therapy for stage IV inflammatory breast cancer (IBC). This study aims to determine indicators of prognosis, including primary tumor resection, for stage IV IBC patients.

METHODS: Using the National Cancer Data Base, female patients diagnosed 2010-2013 with unilateral a priori metastatic T4d invasive adenocarcinoma of the breast were identified. We conducted propensity score matched analysis to balance confounders of surgery versus no-surgery. Stratified log-rank test and double-robust estimation under the Cox model were used to assess the effect of surgery, and margins, on overall survival (OS) in the propensity score matched cohort.

RESULTS: Of 1266 patients, 41% underwent surgery. In the unmatched cohort, median OS of the surgery and no-surgery groups was 36 and 20 months, respectively (p < 0.001). In the matched cohort (n = 588), the median OS of surgery and no-surgery groups was 29 and 27 months, respectively (p = 0.052). Patients with negative margin surgery (p = 0.024), hormone receptor-positive (p = 0.019), HER2-positive disease (p < 0.0001), treated with chemotherapy (p < 0.0001) and hormonal therapy (p < 0.0001), had better survival. Those with brain metastases had increased risk of death (p < 0.0001).

CONCLUSION: This study represents the largest cohort of metastatic IBC patients, and identified negative margin surgery, systemic therapy, hormone receptor and HER2-positive disease as factors associated with improved outcomes. While these findings should be interpreted cautiously, they may be used to guide further investigations into local control and quality of life in this patient population with limited treatment options.