Multiple chemotherapy (CT) lines in metastatic breast cancer (MBC): Which survival benefit for women with hormone receptor (HR)-positive disease?

Abstract

589 Background: Although the development of modern systemic therapies has clearly improved outcome of patients with MBC, the true impact of further CT on overall survival (OS) and QoL of these women is still debated. The aim of this study was to determine which benefit could be brought by successive CT lines in patients with HR-positive disease, aiming to identify factors affecting outcome and survival. Methods: This retrospective analysis included 980 women treated with CT for MBC at our Institution over a eight year period (July 2000-July 2008). With OS data updated in March 2010, the median follow-up was 146 months (range 48-198), 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 for first line to 8.2 months for 7 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 third line (median 5.2 months, range 4.8-6.2). No statistically significant difference was found between HR-positive and HR-negative patients in terms of OS and TTF by each CT line. In univariate analysis factors positively linked to a longer duration of TTF for each CT line were positive hormonal receptor status, more than 3 hormonotherapy lines, 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, in both HR-positive and negative populations (p<0.001). Conclusions: Our results support the benefit of multiple lines of CT in a significant subset of women treated for MBC, since each CT line may contribute to a longer OS. Of interest, such a benefit was also observed for patients with HR-positive disease, although the number of hormonotherpy lines received did not significantly influence the outcome.