Predictors of central nervous system metastasis in patients with metastatic breast cancer. A competing risk analysis of 579 patients treated with epirubicin-based chemotherapy

In order to identify factors predictive of central nervous system (CNS) metastasis, we reviewed the histories of 579 patients treated with epirubicin-based chemotherapy for metastatic breast cancer. Statistical analysis included Kaplan-Meier survival plots, Cox's regression analysis and competing risk analysis using the cumulative incidence. Median follow-up-time was 137 months (range 0-183+). In this period, one hundred and twenty-four patients (21.4%) developed CNS metastasis. Lung, liver, and lymph node metastases and oestrogen receptor negative or unknown tumor were predictive as well. However, increased pretreatment lactate dehydrogenase (LDH) concentration in serum above the upper normal limits was the strongest single risk factor and should therefore be measured. The risk of CNS metastasis differed considerably among risk groups. Patients without risk factors had a cumulative incidence on 9%, compared to a cumulative incidence of 42%, when the serum LDH concentration was elevated to more than twice the upper normal limits.