Abstract
BACKGROUND
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.
METHODS
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.
RESULTS
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.
CONCLUSIONS
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. Cancer 2008. © 2008 American Cancer Society.