Impact of Central Nervous System International Prognostic Index on the Treatment of Diffuse Large B Cell Lymphoma

Background The central nervous system international prognostic index (CNS-IPI) is being used widely for the identification of patients with diffuse large B cell lymphoma (DLBCL) with a high risk of central nervous system (CNS) relapse. The aim of our study is to confirm the value of the CNS-IPI in predicting CNS relapse in our young study population and to evaluate its impact on the selection of patients for CNS prophylaxis. Methods We retrospectively reviewed patients diagnosed with DLBCL who were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) regimen from January 2010 till December 2018. Correlation between CNS-IPI and cumulative incidence of CNS relapse and time to CNS relapse was examined through Kaplan-Meier plots. Median time to CNS relapse and median overall survival after CNS relapse were also estimated using the Kaplan-Meier plots.  Results A total of 354 patients were included. The median age was 46 years. Overall, 5% of the patients developed CNS relapse. Median survival after CNS relapse was seven months. Two-year CNS relapse rates according to CNS-IPI were 0.7%, 5.1%, and 26% for low, intermediate, and high-risk, groups respectively. On multivariate analysis, poor performance status (p=0.045), involvement of two or more extranodal sites (p= 0.021), involvement of bone marrow (p= 0.029), and renal or adrenal glands (p= 0.006) significantly correlated with CNS relapse. Considering the CNS-IPI and high-risk anatomical sites (breast, uterus, testis, and epidural space), 26% of our patients with DLBCL would have needed prophylaxis. Conclusion Although CNS-IPI helps in better selection of DLBCL patients for CNS prophylaxis, it can possibly increase the number of patients exposed to unnecessary prophylaxis. More investigational biomarkers are needed to better refining high-risk patients.