Clinical Outcomes of Metastatic Breast Cancer: Comparison between Initially Metastatic Breast Cancer (IMBC) and Recurrence Metastatic Breast Cancer (RBC).

Abstract

Abstract Purpose: The clinical course of patients with initially metastatic breast cancer (IMBC) can differ from those with recurrent metastatic breast cancer (RBC), since patients with IMBC often have locally-advanced disease and have no history of drug therapy for breast cancer. The objective of this study was to compare IMBC and RBC in terms of overall survival (OS) (from the date of first distant metastases to the date of death or last follow-up), prognostic factors, progression-free survival (PFS) (from the date of first distant metastases to the date of disease progression or last follow-up), overall response rate to first-line therapy for metastatic disease.Patients and Methods: A retrospective analysis of the medical records of patients with metastatic breast cancer diagnosed between 2002 and 2007 was performed.Results: The analysis included 299 patients of whom 100 patients (33%) had IMBC and 199 patients (67%) had RBC. The median follow-up was 22months and median OS was 34 months. With regards to clinical characteristics, patients with IMBC had a higher incidence of cT4 (61% vs. 11%, P<0.001) and cN2-3 (51% vs. 10%, P<0.001) than those with RBC. No significant difference was found in the dominant metastatic site between two groups. In terms of proportions of subtypes based on expression profiles of ER, PgR, HER2 (HR+HER2−/HR+HER2+/HR−HER2+/HR−HER2− (triple-negative)), no significant differences were found (55/10/15/20% vs. 61/8/15/16%, P=0.720). In the IMBC, the proportion of patients who received chemotherapy as a first-line therapy was significantly greater (53% vs. 33%, P=0.004). No significant difference was found in the median OS (27 months vs. 38 months, P=0.553). Multivariate analysis showed that independent negative prognostic factors for the RBC group included cT4 and cN3 of a primary focus, disease-free interval (DFI) of less than 60 months, liver or central nervous system as dominant metastatic site, and triple-negative subtype, whereas for the IMBC group, negative prognostic factors included cN3 and triple-negative subtype but not dominant metastatic site. For patients whose metastasis was treated with first-line chemotherapy (n=118), no significant difference was found in overall response rate between the two groups (60% vs. 49%, P=0.157) but PFS was found to be significantly better for the IMBC group (7months vs. 4months, P=0.029). For triple-negative patients, in the IMBC group the overall response rate to first-line chemotherapy found to be significantly better (70% vs.38%, P=0.027). For patients who were treated with first-line hormone therapy (n=155), no significant difference was found in PFS between the two groups (8months vs. 10months, P=0.4141) but overall response rate was found to be significantly better for the IMBC group (53.8% vs. 24.1%, P=0.001). However, the therapeutic benefit didn't significantly contribute to prolongation of OS.Conclusion: Significant differences were found in the clinical characteristics of patients and the therapeutic benefit of first-line therapies between the IMBC and RBC groups, whereas no difference was found in OS. Triple-negative subtype and cN3 were found to be independent negative prognostic factors common to both groups. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3055.