Prognostic indexes in follicular lymphoma: a comparison of different prognostic systems

The International Prognostic Index (IPI), initially designed for aggressive lymphomas, is also used in follicular lymphoma (FL) and other indolent lymphomas. Two new prognostic indexes have recently been proposed for FL [the Italian Lymphoma Intergroup (ILI) Index and the Follicular Lymphoma International Prognostic Index (FLIPI)].

Three indexes, IPI [age >60 years, extranodal involvement two or more sites, elevated lactate dehydrogenase (LDH), Eastern Cooperative Oncology Group performance status > or =2, stage > or =3], ILI (age >60 years, extranodal involvement two or more sites, elevated LDH, male sex, B symptoms, erythrocyte sedimentation rate > or =30 mm first hour) and FLIPI (age >60 years, stage > or =3, elevated LDH, nodal involvement five or more, haemoglobin level < or =12 g/dl) were calculated in 411 patients with FL.

Overall concordance between the three indexes was 54%. A total of 126 (31%) patients were included in the high-risk group according to IPI, 131 (32%) according to ILI and 157 (38%) after FLIPI application. Ten-year overall survival rates after applying the prognostic indexes (IPI, ILI and FLIPI) were, respectively: 72%, 71% and 72%, in the low-risk group; 51%, 60% and 49% in the intermediate-risk group; and 24%, 16% and 31% in the high-risk group.

In this series, all three indexes, IPI, ILI and FLIPI, were useful to classify FL patients into differentiated risk groups, although the FLIPI identified a larger proportion of high-risk patients than the IPI and ILI.