Occult central nervous system involvement in patients with metastatic breast cancer: prevalence, predictive factors and impact on overall survival

Background: As screening central nervous system (CNS) imaging is not routinely performed, the incidence and clinical relevance of occult CNS metastases in advanced breast cancer is unknown. Patients and methods: All patients screened for participation in one of four clinical trials were included; each of the trials excluded patients with known CNS involvement and required screening CNS imaging. A cohort of breast cancer patients with symptomatic CNS metastases was identified from the IU Cancer Center Tumor Registry for comparison. Results: From November 1998 to August 2001, 155 screening imaging studies were performed. Twenty-three patients (14.8%) had occult CNS metastases. HER-2 overexpression (P=0.02) and number of metastatic sites (P=0.03) were predictive of CNS involvement by multivariate analysis. Median survival from time of metastasis (1.78 versus 2.76 years; P<0.0001) and from screening (4.67 versus 10.4 months; P=0.0013) was shorter in patients with than without occult CNS metastasis. Survival among patients with occult CNS metastasis was similar to patients with symptomatic CNS disease. Conclusions: Patients with CNS involvement, whether occult or symptomatic, have an impaired survival. Occult CNS metastasis is relatively common, but impact on survival of treating occult CNS disease in patients with progressive systemic metastases is questionable.