Chemotherapy response and survival of inflammatory breast cancer by hormone receptor- and HER2-defined molecular subtypes approximation: an analysis from the National Cancer Database.

PURPOSE

To study the impact of hormone receptor (HR)- and human epidermal growth factor receptor 2 (HER2)-defined subtypes on survival of inflammatory breast cancer (IBC), and to determine whether sensitivity to neoadjuvant chemotherapy (NAC) varies with subtypes in a large IBC population.

METHODS

We analyzed 593 IBCs with known HR/HER2 statuses between 2010 and 2011 from National Cancer Database. We compared pathologic complete response (pCR) rates among four molecular subtypes by Chi-square test. Overall survival (OS) was compared among four subtypes and patients with or without pCR using log-rank test. Multivariate Cox model was performed to identify the impact of molecular subtype and other prognostic factors on OS.

RESULTS

Of the 593 patients included, 231 (39.0 %) patients had HR+/HER2- tumors, 98 (16.5 %) had HR+/HER2+ disease, 112 (18.9 %) were HR-/HER2 + patients, and 152 (25.6 %) had triple-negative subtype. The pCR rates differed significantly by subtype (P < 0.001): HR-/HER2+ showed the highest, and HR+/HER2- exhibited the lowest. Multivariate analysis showed that triple-negative and HR+/HER2- IBCs had significantly worse survival compared with HR+/HER2+ or HR-/HER2+ subtype (P < 0.01 for all comparisons). Additional factors associated with worse OS included more comorbidities, lack or incomplete surgical resection, absence of radiotherapy, lack of hormone therapy, and more advanced stage.

CONCLUSIONS

IBC is an aggressive heterogeneous disease with distinct molecular subtypes associated with differential outcomes and sensitivities to NAC. Unlike in noninflammatory breast cancer, in IBC HR + disease was not associated with favorable prognosis. Triple-negative and HR+/HER2- subtypes are independent predictors for suboptimal OS in IBC.