Abstract P3-13-10: Treatment patterns and benefit of later lines of chemotherapy in metastatic breast cancer: A retrospective cohort study
Authors: Lindman H , Svanström C , Lidbrink E 
Published: August 2014

Introduction: The treatment of metastatic breast cancer (MBC) lacks evidence beyond second or third line, but later lines are frequently used in clinical practice. The need for guidelines and studies with longer follow-up makes this area of particular interest for deeper investigation and analysis. We aimed to describe the clinical practice and outcome from later lines of chemotherapy of MBC in Sweden and to find out if the effect of the two first lines could foresee effects in later lines.

Patients and Methods: Patients with MBC treated after year 2009 were identified in our treatment database (RealQ®) in Uppsala University hospital. Of 321 patients with MBC, 165 had received at least one line of chemotherapy and were included for a deeper analysis of tumor factors, response, time-to-treatment failure (TTF), reasons for termination of therapy and overall survival (OS). There were 93 deceased patients, who allowed for a complete analysis of treatment pattern and time from last treatment to death. Subgroup analyses were performed based on tumor biology, age, adjuvant therapy and response or TTF of the two first lines of chemotherapy. Survival times were calculated from diagnosis of metastatic disease and start of first and third line of chemotherapy, respectively.

Results: The median age was 60 years at diagnosis of MBC and 13% were triple negative, 18% HER2-positive and 69% HER2-negative/ER-positive (luminal). The 165 patients received together 553 lines of chemotherapy with a median follow-up of 34 months. The deceased patients were treated with mean 3.6 lines (median 3, range 1-12) and the median time from last treatment to death was only 4.6 weeks. The most used regimens were capecitabine, paclitaxel, FEC, vinorelbine and docetaxel in that order, with an overall response rate (OR) of 47%, 53%, 57%, 23% and 63%, respectively. In HER2-positive patients, 82% of the lines were accompanied by trastuzumab or lapatinib. The OR in first line was 63% and between 23-48% in line two to seven. The mean TTF increased until line three and was relatively stable through the first seven lines (mean 103-182 days). Response to the first two regimens did not predict for better OS, but long TTF (&gt;30 weeks) after the first two lines was associated with a significant survival benefit (median 77 vs. 29 months). So did age below 50 years compared to 50-69 and +70 years (median 90 vs. 54 and 32 months) and HER2-positive disease compared to luminal and triple negative MBC (median 80 vs. 49 and 15 months). Response pattern in early lines could not predict for the response in later lines in the individual patient.

Conclusions: We here present a cohort of MBC patients treated in clinical routine with long follow-up of given chemotherapy lines. Later lines of chemotherapy (from the third to the seventh) created surprisingly good response and long TTF in clinical practice. Long TTF after the two first lines of chemotherapy, but not response, correlated with increased survival from the third line and on. Younger patients and HER2-positive patients showed the best OS with remarkable long survival times.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-13-10.