Which benefit from subsequent chemotherapy lines beyond the second for women with metastatic breast cancer? Evidence from a single-center retrospective analysis of survivorship.

Abstract

255 Background: Although the true impact of chemotherapy (CT) in metastatic breast cancer (MBC) is still debated, in the routine clinical practice an increasing number of women asking for further treatment after progression receive subsequent CT lines. This study aimed to assess which benefit could be brought by the succession of CT lines in patients treated for MBC and to identify women who benefit from these treatments. Methods: This retrospective analysis included 980 women treated with CT for MBC at our Institution over a 7-year period (May 1999-July 2006). With overall survival (OS) data updated at December 1, 2008, the median follow-up was 125 months (range 48-192), OS and time to treatment failure (TTF) were calculated according to the Kaplan-Meyer method for each CT line. Cox proportional hazards model was used to identify factors that could influence TTF and OS. Results: Median OS evaluated from day 1 of each CT line decreased with the line number from 34.8 months (980 patients, 1st line, range 4-208) to 22.6 months (838 patients, 2nd line), 14.6 months (684 patients, 3rd line), 12.4 months (302 patients, 4th line), 9.4 months (88 patients, 5th line), 8.2 months (45 patients, seven or more lines). Median TTF ranged from 9.2 months to 7.8 and 6.4 months for the first, second and third line, respectively, with no significant decrease observed beyond the 3rd line (median 5.2 months, range 4.8-6.2). In univariate analysis factors positively linked to a longer duration of TTF for each CT line were positive hormonal receptor status, absence of liver metastasis, adjuvant CT exposure, response to CT for the metastatic disease; in the multivariate analysis the duration of TTF for each CT line was the only one factor with significant impact on survival benefit for subsequent treatments (p<0.001). Conclusions: CT beyond the 2nd line may be beneficial in a significant subset of women treated for MBC, with improved TTF and OS. These findings could help physician in planning an appropriate strategy of subsequent schedules for women with symptomatic MBC who responded to their 1st line CT, while non responder patients should be considered for clinical trials.