Purpose: To study prognostic factors after high-dose chemotherapy (HDC) for patients with stage IV oligometastatic breast cancer.
Patients and methods: Sixty patients with minimal metastatic disease amenable to local therapy enrolled onto a prospective HDC trial were analyzed for potential prognostic factors. Tumor blocks were retrospectively collected from referring institutions.
Results: Median follow-up was 62 months (range, 4 to 120 months). Median relapse-free survival (RFS) and overall survival (OS) times were 52 and 80 months, respectively. Five-year RFS and OS rates were 52% (95% confidence interval [CI], 39% to 64%) and 62% (95% CI, 49% to 74%), respectively. HER-2 expression, number of tumor sites, primary axillary nodal ratio (number of positive nodes divided by number of sampled nodes), number of positive axillary nodes, and delivery or omission of radiotherapy to metastases correlated with RFS. HER-2 overexpression and more than one site were independent adverse risk factors for RFS. HER-2 and the axillary nodal ratio were independent predictors of OS. The following prognostic categories for RFS were established (RFS rate, median RFS): good risk, no factors (77%, 80 months); intermediate risk, one factor (41%, 28 months); and poor risk, both factors (10%, 10 months).
Conclusion: Long-term results in patients with oligometastatic breast cancer are encouraging but need validation in prospective randomized studies. HER-2 expression, number of sites, and primary nodal ratio are independent outcome predictors. Confirmation of these observations in this selected population would imply the need for reevaluation of the current tenet that early detection of metastatic breast cancer recurrence is of no benefit.