Ki-67 is a strong predictor of central nervous system relapse in patients with mantle cell lymphoma (MCL)

High Ki-67 is strongly associated with the risk of CNS relapse in patients with mantle cell lymphoma. Two-year incidence of CNS relapse in patients with Ki-67 ≥ 30 exceeds 25%. The incidence was not decreased by rituximab, high-dose cytarabine, high-dose methotrexate or consolidative ASCT. Development of new prophylactic strategies for CNS involvement is mandatory in patients with high Ki-67. Central nervous system (CNS) relapse is an uncommon but challenging complication in patients with mantle cell lymphoma (MCL). Survival after CNS relapse is extremely poor. Identification of high-risk populations is therefore critical in determining patients who might be candidates for a prophylactic approach. A total of 608 patients (median age, 67 years; range 22–92) with MCL newly diagnosed between 1994 and 2012 were evaluated. Pretreatment characteristics and treatment regimens were evaluated for their association with CNS relapse by competing risk regression analysis. None of the patients received intrathecal prophylaxis. Overall, 33 patients (5.4%) experienced CNS relapse during a median follow-up of 42.7 months. Median time from diagnosis to CNS relapse was 20.3 months (range: 2.2–141.3 months). Three-year cumulative incidence of CNS relapse was 5.6% [95% confidence interval (95% CI) 3.7% to 8.0%]. Univariate analysis revealed several risk factors including blastoid variant, leukemic presentation, high-risk MCL International Prognostic Index and high Ki-67 (proliferation marker). Multivariate analyses revealed that Ki-67 ≥ 30 was the only significant risk factor for CNS relapse (hazard ratio: 6.0, 95% CI 1.9–19.4, P = 0.003). Two-year cumulative incidence of CNS relapse in patients with Ki-67 ≥ 30 was 25.4% (95% CI 13.5–39.1), while that in the patients with Ki-67 < 30 was 1.6% (95% CI 0.4–4.2). None of the treatment modalities, including rituximab, high-dose cytarabine, high-dose methotrexate or consolidative autologous stem-cell transplant, were associated with a lower incidence of CNS relapse. Survival after CNS relapse was poor, with median survival time of 8.3 months. There was no significant difference in the survival by the site of CNS involvement.