Background
The central nervous system international prognostic index [CNS-IPI]is being usedwidely for the identification of patients with diffuse large B cell lymphoma [DLBCL]with highrisk of 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 the impact on selection of patients for CNS prophylaxis.
Methods
We retrospectively reviewed patients with pathological diagnosis of DLBCL who were treated with R-CHOP [rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone] regimen from January 2004 till December 2016 with no evidence of CNS involvement on diagnosis. Different demographic, disease characteristics and treatment given including the use of intrathecal chemotherapy prophylaxis were collected. Correlation between CNS-IPI and CNS relapse was examined through chi square test. Median time to CNS relapse and median overall survival [OS] after CNS relapse were estimated using the Kaplan-Meier plots.
Results
354 patients were included. Median age was 46 years. 52 [15%] patients were given intrathecal chemotherapy [ITC] prophylaxis, of whom CNS-IPI was high in 7[13%]. Overall, 5% of the patients [n = 17] developed CNS relapse.The median survival after CNS relapse was 7 months. The rate of CNS relapse in patients with low, intermediate and high risk CNS-IPI was 0.6%, 3% and 22% respectively [p = < 0.001].On multivariate analysis, involvement of bone marrow [p = 0.039]and renal or adrenal glands[p = 0.023]significantly correlated with CNS relapse. Considering theCNS-IPI and high risk anatomical sites [breast, uterus, testis and epidural space], 26% of our patients with DLBCLwould have needed prophylaxis.
Conclusion
Although CNS-IPI helps in better selection of DLBCL patients for CNS prophylaxis, it will significantly and possibly unnecessarily increase the number of patients exposed to prophylaxis. More investigational biomarkers and methods are necessary to better refining high risk patients.