Clinical characteristics and outcomes of patients with prostate cancer and parenchymal brain metastases (PBM).

Abstract

187 Background: Parenchymal brain metastases' (PBM's) are rare in prostate cancer (PCa), but the introduction of novel therapies that prolong life for metastatic disease has raised the possibility that the distribution of disease may be changing as patients live longer. In an effort to establish the clinical characteristics and outcomes of PBM as a comparator for future studies, we reviewed all cases at our institution over a 13 year period. Methods: Patients (pts) diagnosed with PBM at Memorial Sloan-Kettering Cancer Center between 2000 and 2010 were retrospectively identified by billing codes for prostate cancer, brain metastases, and no additional primary cancers. Additional cases since 2010 were manually collected prospectively. Direct extension of osseous skull metastases or leptomeningeal disease were not considered PBM. Demographic, clinical, and pathologic characteristics were recorded. Results: 5,474 pts with metastatic PCa and no other primary malignancy were identified of whom 21 had PBM. An additional four PBM cases were prospectively identified, for a total of 25 pts. Twenty two pts (88%) had prostate adenocarcinoma (adeno), of which 14 had Gleason 8 or more disease, 20 had castration resistant disease, and nine had prostate-specific antigen (PSA) less than 5ng/mL. The other three (12%) had atypical histologies (osteosarcoma, small cell carcinoma, and high grade neuroendocrine carcinoma). Median time from diagnosis of PCa to diagnosis of PBM was 3.7 years (range 0 to 19.8) and from discovery of metastatic PCa to PBM was 2.3 years (range 0 to 10). At the time of PBM diagnosis all pts had 1 or more additional site of disease - bone metastases in 20 (80%), lung in 13 (52%), liver in nine (36%). Treatments included whole brain RT in 10 (45%), surgery +/- RT in 8 (36%) and stereotactic RT in 2 (9%). Median overall survival from diagnosis of PBM was 4.3 months (0.7-18.1) in adeno pts compared with 0.7 months (0.7-1.0) in atypical histology pts. Only four pts (16%) survived 12 or more months. Conclusions: In this contemporary cohort, PBM cases were often associated with PCa of atypical histology, high Gleason grade, frequent visceral disease, and low PSA production. Survival was poor after diagnosis of PBM despite treatment. These data can be used as a comparator to track whether treatment with novel PCa therapies is altering the incidence and characteristics of CNS involvement.