A Retrospective Analysis of Primary Tumour Histology and Survival in Breast Cancer Patients Developing Symptomatic Brain Metastases Treated with Whole Brain Radiotherapy (WBRT) at Mount Vernon Cancer Centre (MVCC).

Abstract

Abstract Background: The purpose of this study was to determine the influence of primary tumour histology on survival following WBRT for brain metastases in patients with breast cancer.Methods: From treatment records we identified 294 patients with brain metastases and a diagnosis of primary breast cancer who were treated with WBRT at MVCC from January 2000 until December 2008. We obtained information from case notes and original pathology reports regarding TNM staging and receptor status: Estrogen (ER), progesterone (PR) and human epidermal growth factor receptor-2 (HER-2). Dates of diagnosis and death were sourced from records at MVCC, the Thames Cancer Registry and GP practices.Results: We obtained receptor status, TNM staging and dates of death for 294 patients; 19 were excluded as date of death could not be verified. The dates of primary diagnosis for the study cohort ranged from 1983 to 2008. The median age at diagnosis was 52 (range 24-81, interquartile range 42-62).Analysis of age at primary diagnosis expressed as < 50 or ≥ 50 demonstrated improved survival in the younger age group (HR 0.64 95% CI 0.50-0.83). Time to brain relapse amongst patients receiving WBRT was not related to initial tumour size (p=0.8) but was related to the number of affected nodes (reduced by 9 months per node, p=0.038) and women with (non-brain) metastatic disease at diagnosis had WBRT on average 2.4 years earlier than those that did not (p=0.004). TNM staging did not affect post WBRT survival. After adjusting for age at diagnosis (<,≥50), post WBRT survival was not affected by age at treatment. Controlling for the influence of age at diagnosis, Cox regression analysis of survival post WBRT demonstrated improved survival for ER positive patients (HR 0.66 95% CI 0.49-0.90). Survival post WBRT was not significantly influenced by HER-2 (HR 0.81 95% CI 0.55-1.19) or PR (HR 0.91 95% C.I. 0.63-1.33) status. Patients who experience late brain relapse (> 4 years post diagnosis) have slightly better survival post WBRT (HR 0.77, p=0.054). ER positive patients in this study developed brain metastases on average 1.8 years later than ER negative patients (95% CI 0.9-2.8).Conclusions: In this cohort ER positive patients who relapse in the brain do so later and live longer following WBRT (figure 1). Our data suggests that HER-2 status has little effect on post WBRT survival. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4110.