What is the real risk of central nervous system involvement in mantle cell lymphoma?

BACKGROUND Extranodal involvement, including central nervous system (CNS), is a frequent event in patients with mantle cell lymphoma (MCL). However, the incidence, risk factors, and impact on outcome remain controversial. PATIENTS AND METHODS Main clinical, biological, and evolutive features of 82 patients (60 males/22 females; median age: 61 years) diagnosed with MCL (blastoid, 26%) in a single institution were analyzed for risk of CNS involvement and prognosis. RESULTS Most patients had advanced stage and intermediate or high-risk International Prognostic Index (IPI). Eleven patients eventually developed CNS involvement with an actuarial 5-year risk of 26% (95% confidence interval 10% to 42%). In one asymptomatic patient, cerebrospinal fluid infiltration was detected at staging maneuvers (1/62; 1.6%). The remaining 10 patients developed neurological symptoms during the course of the disease (median time from diagnosis, 25 months). Initial variables predicting CNS involvement were blastoid histology, high proliferative index measured by Ki-67 staining, high lactate dehydrogenase (LDH) and intermediate- or high-risk IPI. Histological subtype and serum LDH maintained significance in multivariate analysis. Treatment of CNS infiltration consisted of intrathecal chemotherapy (two cases), and intrathecal chemotherapy plus systemic treatment (seven cases). Median survival after CNS involvement was 4.8 months, patients with this complication having shorter survival than those with no CNS disease. CONCLUSION This study confirms the high incidence of CNS involvement in MCL patients. Treatments aimed at preventing this complication are warranted.