Use and duration of chemotherapy in patients with metastatic breast cancer according to tumor subtype and line of therapy

Benefits of chemotherapy vary in patients with metastatic breast cancer (MBC). This article describes the impact of tumor subtype and the line of therapy on the duration of chemotherapy. Clinicopathologic characteristics were extracted from the medical records of 199 consecutive patients with MBC at Dana-Farber Cancer Institute and analyzed according to subtype. Tumor subtypes were classified as hormone receptor (HR)-positive, triple-negative (TNBC), or HER2-amplified breast cancer. Duration of chemotherapy of each line was defined as the start of a chemotherapy regimen to the start of the next line of therapy as a result of progression or toxicity. There were 96, 44, and 59 patients with HR(+), TNBC, and HER2-amplified breast cancer, respectively. Median age at MBC diagnosis was 53 years. Median overall survivals were 32 and 54 months for HER2-amplified disease, 36 months for HR(+) breast cancer, and 17 months for TNBC (P