Comparison of conventional prognostic indices in patients older than 60 years with diffuse large B‐cell lymphoma treated with R‐CHOP in the US Intergroup Study (ECOG 4494, CALGB 9793): consideration of age greater than 70 years in an elderly prognostic index (E‐IPI)

Abstract

To assess if immunochemotherapy influenced the prognostic value of IPI in elderly diffuse large B‐cell lymphoma (DLBCL) patients, we evaluated the performance of the standard International Prognostic Index (IPI) and following modifications: age adjusted (AA)‐IPI, revised (R)‐IPI, and an elderly IPI with age cut‐off 70 years (E‐IPI) in patients >60 years treated with RCHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone). In 267 patients, by IPI/AA‐IPI 60% were high‐intermediate, 53% high and 12% low risk. With R‐IPI, 60% were poor risk and none very good risk. Using E‐IPI, 45% were high‐intermediate/high risk and 27% low risk. No differences in outcome were seen in the low/low‐intermediate groups with IPI/AA‐IPI. For E‐IPI, failure‐free survival (FFS) and overall survival (OS) were significantly different for low/low‐intermediate groups. No differences were detected in the four indices with model fit/discrimination measures; however, E‐IPI ranked highest. For elderly R‐CHOP treated patients, distribution of IPI/AA‐IPI skewed toward high/high‐intermediate risk with no differences in FFS/OS between low/low‐intermediate risk. In contrast, with E‐IPI, more are classified as low risk with significant differences in FFS/OS for low‐intermediate compared to low risk. The R‐IPI does not identify a very good risk group, thus minimizing its utility in this population. The prognostic discrimination provided by the E‐IPI for low and low‐intermediate elderly DLBCL patients needs validation by other datasets.