Prognostic Impact of the Tumor Marker CA 15-3 in Patients With Breast Cancer and Bone Metastases Treated With Palliative Radiotherapy

BACKGROUND The aim of the study was to explore the prognostic impact of different abnormal blood tests and the tumor marker CA 15-3 as well as established parameters such as disease extent and receptor status in patients with bone metastases from breast cancer who received palliative radiotherapy in addition to contemporary systemic treatment. METHODS This was a retrospective uni- and multivariate analysis of 118 female patients treated in the time period from 2007 to 2014 (median follow-up 28 months). RESULTS The median age was 61 years and the median time interval from the initial diagnosis of breast cancer was 57 months (median time interval from metastatic disease to radiotherapy was 7 months). Only 16% of patients had normal serum CA 15-3. HER2 receptor status correlated with CA 15-3. The median survival was 17.6 months (lowest CA 15-3 quartile), 14.7 months (intermediate), and 6.9 months (highest quartile) (P = 0.002). However, multivariate analysis showed that survival was influenced by extent of extra-skeletal metastases, pleural metastases/effusion, lung metastases, estrogen receptor status, serum C-reactive protein, and anemia with need for blood transfusion (all P < 0.05) rather than CA 15-3. CONCLUSIONS Survival was highly variable. The tumor marker CA 15-3 did not provide independent prognostic information. Nevertheless, the results of simple blood tests contributed to the multivariate prognostic model.