Benefit from Chemotherapy in Metastatic Breast Cancer: A Retrospective Analysis at the BC Cancer Agency—Vancouver Island Centre.

e12505 Background: Chemotherapy (CTX) can palliate symptoms and modestly prolong survival in patients with metastatic breast cancer (MBC). From clinical trials we have an understanding of the toxicity, response rate, and progression free survival associated with earlier lines of CTX. The difficulty for both medical oncologists and patients is in estimating the likelihood of benefit from CTX in later lines of treatment, and how response in prior lines influences that estimation. Methods: We performed a retrospective review of 288 patients with Her2-negative or Her2-unknown MBC treated with at least two lines of CTX to identify predictors of benefit or lack of benefit to further lines of therapy at the BC Cancer Agency (Vancouver Island Centre) from 2000-2010. We assigned the score of “Benefit” to those who had improvement in disease symptoms and/or improvement on imaging, and then examined for predictors of that Benefit. Initial improvement but then progression prior to the completion of 6 cycles of CTX, or no change in symptoms or imaging through the 6 cycles, were scored as Minimal-Benefit. Treatment which was stopped prior to cycle 4 due to worsening of symptoms or progression on imaging, or if death occurred prior to cycle 4, was scored as No-Benefit. Results: 288 patients received two lines of CTX; 36% had Benefit to 1st line CTX, and 18% had Benefit to 2nd line CTX. 3rd line CTX was given to 163 patients and 14% had Benefit. The Benefit in lines 4, 5 and 6, were 12% or less. If Benefit or Minimal-Benefit was obtained in 1st or 2nd line, the chance of Benefit in line 3 was 18% compared to 8% in those patients who did not have Benefit or Minimal Benefit in the first two lines. The chance of Benefit decreased with subsequent lines of CTX for MBC. Obtaining Benefit to 1st line did not substantially increase the chance of Benefit in 2nd line compared to those who achieved No-Benefit in 1st line. Conclusions: In an unselected, non-clinical trials, population of patients with MBC treated with CTX the chance of Benefit was 14% or less in 3rd and subsequent lines of CTX. Response in earlier lines of treatment modestly modified the likelihood of such benefit.