A study of factors determining outcome of patients receiving third line chemotherapy for metastatic breast cancer: The Royal Marsden Hospital experience

Abstract

657 Background: Metastatic breast cancer is increasingly treated with multiple lines of chemotherapy. We studied the factors determining the outcome of patients receiving third line chemotherapy for metastatic breast cancer Methods: This is retrospective study of 149 consecutive patients from the Royal Marsden Hospital chemotherapy database recorded to have received third line chemotherapy for metastatic breast cancer. The chemotherapy regimens and best response to chemotherapy for all three lines of chemotherapy were recorded. The time to progression (TTP) and survival after third line chemotherapy were also studied. Chi square and log rank tests were used to analyse differences in response rates (RR) and (TTP)/survival respectively. Results: 149 patients were studied with a median age of 52 (range 25 -80). The median TTP and survival was 4 months (range 1–25) and 8 months (range 1–52) respectively. Eighteen different chemotherapy regimens were used. The RR for third line chemotherapy was 30.2% (45/149). There was no significant difference in the TTP and survival of patients treated with different chemotherapy regimens (p= 0.82 and 0.44) respectively. We identified a subgroup of patients who had a poor outcome after third line chemotherapy. These patients did not respond to the first two lines of chemotherapy and had a response rate of 20.2% (10/49) compared to the rest of the cohort, 35% (35/100), p= 0.068. The TTP (3 Vs 4 months, p = 0.033) and survival, (6 Vs 9 months, p = 0.027) of this subgroup was significantly shorter than the rest of the cohort. The median time to death after progression in this subgroup was 2 months. Conclusions: The chemotherapy regimen used does not influence RR, TTP or survival in patients receiving third line chemotherapy for metastatic breast cancer. Patients not responding to the first two lines of chemotherapy have a significantly shorter TTP and survival. Best supportive care or experimental chemotherapy should be considered as options for these patients. No significant financial relationships to disclose.