International and Italian prognostic indices in follicular lymphoma

The International Prognostic Index (IPI), initially designed for aggressive lymphomas, has been successfully used in patients with follicular lymphoma (FL). The Italian Lymphoma Intergroup (ILI) created a new prognostic index specific for FL. The aim of this study was to compare which of these two indices is more useful when applied to a large group of FL patients.

Both indices, IPI (age >60 years, extranodal involvement >=2 sites, elevated lactate dehydrogenase, ECOG >=2, stage >=3) and ILI (age >60 years, extranodal involvement >=2 sites, elevated lactate dehydrogenase, male sex, B symptoms, erythrocyte sedimentation rate >=30 mm 1(st) hour) were calculated in a group of 398 FL patients. Overall survival (OS) and progression-free survival (PFS) associated with each prognostic group were calculated according to the Kaplan-Meier method.

The overall concordance between both indices was 73%. According to the IPI 122 patients (31%) were in the higher risk group, whereas according to the ILI 132 (33%) were; concordance between the high risk groups was 66%. The 10-years OS and PFS rates after applying the IPI system were 73% and 37%, respectively, in the low risk groups; 47% and 26%, in the intermediate risk groups and 25% and 2%, in the high risk groups (log-rank=69.2 and 41.3, respectively; p<0.0001). According to ILI index the 10-year OS and PFS were 60% and 34%, respectively, in the low risk groups; 59% and 30%, in the intermediate risk groups and 17% and 0%, in the high risk groups (log-rank=86.6 and 58.5, respectively; p<0.0001).

Both the IPI and ILI index, are useful for classifying FL patients into different risk groups. Although it seems that the ILI index has a higher discriminating power among groups, significant differences were not observed in identifying FL patients with a poor outcome.