Abstract 269P
Background
Up to 40% of patients (pts) with HER2-positive breast cancer (BC) develop brain metastases (BM). Identification of factors associated with long-term survival is important for the improvement of treatment modalities.
Methods
A total of 1160 HER2-positive pts of the BMBC registry were available for this analysis. Long-term survival was defined as overall survival (OS) in the upper third of the survival curve resulting in a cut-off of 23 months. 328 pts were categorized as long-term survivors.
Results
Long-term HER2-positive survivors compared to other pts were significantly younger at BC and BM diagnosis (median 48 vs 53 and 52 vs 57 years, p<0.001), had more often hormone receptor positive tumor biology (ER+ and/or PR+ 65 vs 56%, p=0.009), better ECOG performance status at time of BM diagnosis (ECOG 0-1: 80 vs 56%, p<0.001), lower BM number (n=1 BM 38 vs 25%, p<0.001), lower rate of extracranial metastases at BM diagnosis (69 vs 82%, p<0.001) and lower rate of leptomeningeal metastases (6 vs 11%, p=0.018). Furthermore, long-term survivors were significantly more often treated with a combination of brain surgery and radiotherapy (39 vs 22%, p<0.001) and were significantly more often neurologically asymptomatic at BM diagnosis (28 vs 20%, p=0.005). Median OS in long-term survivors was 45.2 months (95%CI 40.4-47.7). Parameters significantly associated with an assignment in the group of long-term survivors (multivariate logistic regression analysis) are presented in the table. Table: 269P
Multivariate logistic regression in long-term survivors vs short-term survivors
| Parameter at diagnosis | Category | Odds Ratio* | 95% CI | p-value |
| Age** | < 60years | |||
| ≥60 years | 0.59 | 0.38, 0.91 | 0.018 | |
| Hormone receptor | negative | |||
| positive | 1.47 | 0.96, 2.25 | 0.078 | |
| ECOG** | 0-1 | |||
| 2-4 | 0.51 | 0.32, 0.82 | 0.006 | |
| Number of BM | 1 | 0.046 | ||
| 2-3 | 0.66 | 0.39, 1.13 | 0.127 | |
| ≥4 | 0.53 | 0.32, 0.88 | 0.015 | |
| Leptomeningeal metastases | no | |||
| yes | 0.70 | 0.30, 1.66 | 0.421 | |
| Clinical symptoms** | no | |||
| yes | 0.68 | 0.41, 1.14 | 0.147 | |
| Extracranial Metastases ** | no | |||
| yes | 0.58 | 0.36, 0.94 | 0.028 | |
| Chemotherapy*** | no | |||
| yes | 1.40 | 0.86, 2.28 | 0.174 | |
| Anti-HER2 therapy*** | no | |||
| yes | 1.98 | 1.23, 3.19 | 0.005 |
*An odds ratio ≥1 means to have a higher probability to be assigned to the group of long-term survivors ** at diagnosis of BM *** after diagnosis of BM
Conclusions
Our analysis identified factors associated with long-term survival of HER2-positive BC pts with BM and characterized clinical features of this patient cohort. Anti-HER2 targeted therapy after BM is an important factor associated with long-term survival of HER2-positive pts with BM.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
University Medical Center Hamburg-Eppendorf.
Funding
Financial support for the management of BMBC Registry was provided by an unrestricted research grant from Daiichi Sankyo to GBG.
Disclosure
All authors have declared no conflicts of interest.