Clinical outcome in women with HER2-positive de novo or recurring stage IV breast cancer receiving trastuzumab-based therapy

BACKGROUND: Five to 10% of women with newly diagnosed breast cancer have synchronous metastases (de novo stage IV). A further 20% will develop metastases during follow-up (recurring stage IV). We compared the clinical outcomes of women with HER2-positive metastatic breast cancer (MBC) receiving first-line trastuzumab-based therapy according to type of metastatic presentation. PATIENTS AND METHODS: Retrospective analysis of 331 MBC patients receiving first-line trastuzumab-based treatment. Response rates (RR) were compared by the chi-square test. Time-to progression (TTP) and overall survival (OS) curves were compared by the log-rank test. Cox-proportional hazards models were used to study predictors of PFS and OS, including the type of metastatic presentation. RESULTS: Seventy-seven patients (23%) had de novo stage IV disease. Forty-six of these patients underwent surgery of the primary ("de novo/surgery"). Response rates to first-line trastuzumab-based therapy and median progression-free survival did not differ in patients with "recurring", "de novo/surgery" and "de novo" without surgery ("de novo/no surgery) stage IV breast cancer. However, women with "de novo/surgery" stage IV breast cancer had the longest median OS (60 months), and those with "de novo/no surgery" stage IV breast cancer the shortest (26 months). For women with recurring metastatic breast cancer median OS was 40 months (overall log-rank test, p < 0.01). Multivariate analysis confirmed these findings. CONCLUSION: Our analysis shows that response rates and PFS to first-line trastuzumab-based therapy do not differ significantly between de novo and recurring stage IV, HER2 positive breast cancer. The observed difference in OS favoring women with de novo stage IV disease submitted to surgery of the primary tumor could be the result of a selection bias.