Assessment of treatment response with fulvestrant (F) 500 mg in standard clinical practice through a retrospective study: NCT01509625.

Abstract

e11583 Background: The CONFIRM study showed greater efficacy of F500 as compared to F250.Based on these results a dosage change was authorized in Spain.The aim of this study is to describe the efficacy of F500 (progression free survival(PFS) and clinical benefit rate(CBR) in Spanish patients (P) with estrogen receptor (ER+) Metastatic Breast Cancer (MBC) through a retrospective data collection. Methods: After written informed consent, data collection was recorded from clinical records of P who previously had progressed on hormonal treatment and who received at any time F 500 from 1st January 2010 to 31st October 2011. Results: 102 P in 14 centers were included in the study, 93 P were evaluable.Median age was 65 (39-88). Histology: 80.6% ductal ;15% lobulillar. Hormonal receptors: ER+/ PgR+ 77.4%; ER+/PgR- 21.6 %. HER2 status was documented in 80P, 15% of them were HER2+. 45.4% were Ki67 +. Mean from diagnosis to metastatic disease:3.7 years, 19.3% of P had de novo metastatic disease. 21.5% of P had visceral metastases.82.8% of P had good PS (0-1) when F started.F received as 1st line in 7.5%, as 2nd line in 52.7% and 3rdor more in 39.8% of the P. Average cycles administered: 10(3-48). With a median follow up of 16 months (m) since F treatment (1.4-34.4), median PFS was 10.6 m[8.3-13.0]. CBR was 59.1% (12.9%CR, 12.9 PR and 33.3% SD≥ 24 weeks). Median PFS in P with or without CB was 23.3 m and 5.6 m respectively. Median PFS in P with F in 1 st line was 10.3 m, 11.6 m in 2nd line and 9 m in 3rd line or more. No significant differences in CBR were observed between P with or without visceral metastases (58.9 vs 60%). There was a trend in the CBR between HER –ve and +ve groups (64.7% vs 33.3% p = 0.0565). 1-year survival rate was 86% (77.3-92.3). Median Overall Survival was not calculated because only 20 P had died when data were analyzed. More frequent toxicities were: local injection site pain (11.8%), hot flushes (11.8%) and gastrointestinal disorders (8.6%). Conclusions: F500 in real life setting showed a PFS of 10.6 m and got CB in 2/3 of P with a good toxicity profile, in line with phase III trials. In P who achieve a CB the median PFS was almost two years. P with visceral metastases may benefit from F same as those with non visceral involvement.