Effects of second and subsequent lines of chemotherapy for metastatic breast cancer

Background: We assessed the effect of chemotherapy regimens beyond first-line agents on the clinical outcomes in patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC).

Patients and methods: We included 240 patients who were prospectively enrolled into various clinical trials and were receiving cytotoxic chemotherapy for HER2-negative MBC at the National Cancer Center, Korea, from October 2002 to September 2012. Clinicopathologic data were collected for the analysis.

Results: A total of 240, 209, and 166 patients received first-, second-, and third-line chemotherapy, respectively. The median age was 49 years (range, 28-77 years), and most had hormone receptor-positive cancer (n = 177; 73.8%). The median progression-free survival (PFS) was 7.6 months for first-line (PFS1) versus 5.1 months for second-line (PFS2) versus 3.6 months for third-line (PFS3) chemotherapy. The PFS from previous chemotherapy significantly affected subsequent PFS: PFS1 for PFS2, PFS1 ≥ 7.6 months, hazard ratio (HR) 0.647; 95% confidence interval (CI), 0.0.484-0.864 (P = .003); PFS2 for PFS3, PFS2 ≥ 5.1 months, HR 0.676; 95% CI, 0.0.484-0.944; P = .022). The median overall survival was 31.2 months (95% CI, 26.4-36.0 months). Hormone receptor positivity (HR 0.548; 95% CI, 0.261-0.499; P < .001) and PFS1 ≥ 7.6 months (HR 0.361; 95% CI, 0.393-0.765; P < .001) were significant factors for survival on multivariate analysis.

Conclusion: The efficacy of previous treatment significantly affected the outcomes of subsequent treatment. We have confirmed that the succession of chemotherapy is justified in patients with MBC who benefited from previous chemotherapy.