Prognostic significance of HER-2 status in women with inflammatory breast cancer.

Abstract

Inflammatory breast cancer (IBC) is a rare, aggressive form of breast cancer with poorly understood prognostic variables. The purpose of this study was to define the prognostic impact of HER-2 status on survival outcomes of patients with IBC.
In all, 179 patients with IBC, diagnosed between 1989 and 2005, with known HER-2 status, and treated with an anthracycline-based chemotherapy regimen without trastuzumab, were included in the analysis. Patients with HER-2-positive disease who received trastuzumab at the time of disease recurrence were included. Survival outcomes were estimated by the Kaplan-Meier product limit method and compared across groups using the log-rank statistic. A Cox proportional hazards model was fitted to determine the association of survival outcomes with HER-2 status after adjusting for patient and tumor characteristics.
A total of 111 patients (62%) had HER-2-negative disease and 68 (38%) had HER-2-positive disease. The median follow-up among all patients was 35 months. At the time of the analysis, 62 patients (55.9%) with HER-2-negative disease and 42 patients (61.8%) with HER-2-positive disease had a recurrence. Thirty-one patients (73.8%) with HER-2-positive disease who had a disease recurrence went on to receive trastuzumab. On univariate analysis, no statistically significant difference was observed for either recurrence-free survival (P = .75) or overall survival (P = .24) between patients who had HER-2-positive disease and those who had HER-2-negative disease. In a multivariate model, HER-2 status did not appear to significantly affect recurrence-free survival (hazards ratio [HR] of 0.75; 95% confidence interval [95% CI], 0.46-1.22 [P = .241]). In the multivariate model, patients with HER-2-positive disease had a decreased hazard of death (HR of 0.56; 95% CI, 0.34-0.93 [P = .024]) compared with patients with HER-2-negative disease.
HER-2 status, in the absence of trastuzumab, did not appear to significantly affect recurrence-free survival. After adjusting for other characteristics, the addition of trastuzumab in the metastatic setting significantly improved survival in the HER-2-positive group above and beyond that of the HER-2-negative group. This gives us further insight into the biology of this aggressive disease and underlines the major effect of targeted intervention.