Tumor marker analyses in patients with brain metastases: patterns of practice and implications for survival prediction research.

This study aims to explore patterns of practice of tumor marker analyses and potential prognostic impact of abnormal markers in patients with brain metastases from solid tumors. Previously, lactate dehydrogenase (LDH) and albumin were identified as relevant biomarkers. We performed a retrospective analysis of 120 patients with known LDH and albumin treated with whole-brain radiotherapy (WBRT) in two different situations: (1) brain metastases detected at initial cancer diagnosis (n = 46) and (2) brain metastases at later time points (n = 74, median interval 13 months). Twenty-six patients (57 %) from group 1 had at least one tumor marker analyzed, and 11 patients (24 %) had abnormal results. Twenty-two patients (30 %) from group 2 had at least one tumor marker analyzed, and 16 patients (22 %) had abnormal results. When assuming that LDH and albumin would be standard tests before WBRT, additional potential biomarkers were found in 36 % of patients with normal LDH and albumin. Marker positivity rates were for example 80 % for carcinoembryonic antigen (CEA) in colorectal cancer and 79 % for CA 15-3 in breast cancer. Abnormal markers were associated with presence of liver metastases. CA 15-3 values above median predicted shorter survival in patients with breast cancer (median 1.9 vs. 13.8 months, p = 0.1). Comparable trends were not observed for various markers in other tumor types. In conclusion, only a minority of patients had undergone tumor marker analyses. Final group sizes were too small to perform multivariate analyses or draw definitive conclusions. We hypothesize that CA 15-3 could be a promising biomarker that should be studied further.