Outcomes of patients with inflammatory breast cancer by hormone receptor- and HER2-defined molecular subtypes: A population-based study from the SEER program

BACKGROUND: The aim of this study was to evaluate the outcomes of patients with inflammatory breast cancer (IBC), with emphasis on the role of molecular subtypes and radiotherapy. METHODS: A retrospective cohort study to investigate overall survival (OS) and breast cancer-specific mortality (BCSM) in patients with IBC was conducted using data obtained by the Surveillance, Epidemiology, and End Results (SEER) program from 2010–2013. Cox multivariate regression was used to calculate the adjusted Hazard Ratios (aHR). RESULTS: 403 patients were eligible for this study. Patients in the group with hormone receptors (HR)+/HER2- subtype had an OS of 79.6% compared with 89.0 % in the group with (HR)+/HER2+ subtype and 76.8% in the HR-/HER2+ group and 62.9% in the triple-negative (TN) group. BCSM was 16.3% for the HR+/HER2- group, 9.8% for the HR+/HER2+ group, 21.7% for the HR-/HER2+ group, and 30.5% for the TN group. For distant metastases, the results showed that there was a high probability of bone metastasis in HR-positive groups, brain and liver metastasis in HER2-positive groups, and lung metastasis in the TN group. Multivariate analysis demonstrated that estrogen receptor and HER2 positivity were associated with better survival and that the TN subtype had a poorer OS and BCSM compared with other subtypes (P<0.05). Furthermore, patients who received radiotherapy were more likely to have improved survival (P< 0.05). CONCLUSION: Inflammatory breast cancer appears to alter the prognosis in association with the receptor status and molecular subtypes. Radiotherapy was still considered to be a crucial treatment for patients with IBC.