THE NUMBER OF EXTRANODAL SITES IN NODAL PTCL: A PROPOSAL FOR A FEASIBLE PROGNOSTIC MARKER FOR OUTCOMES IN LOW-INCOME COUNTRIES. A COLLABORATIVE STUDY GRUPO DE ESTUDIO LATINO-AMERICANO DE LINFOPROLIFERATIVO (GELL) & T-CELL BRAZIL PROJECT (TCBP)

PTCL accounts for 10-15% of all NHL. As previously demonstrated, Latin America has its own epidemiological distribution, with a high frequency of ATLL and ENKT, likely influenced by distinct genetic profiles and viral epidemiology. 3-year OS is about 40%. Treatment advances have also been limited, except for BV-CHP in some countries. The IPI, which includes extranodal (EN) site as a variable, has been validated for PTCL. However, the specific impact of EN involvement on nodal PTCL (such as PTCL-NOS, AIT, ALCL ALK+/ALK-) and its biological implications remain unclear. Simplification could improve the reproducibility and applicability of these models, especially in low-income countries. To evaluate number of EN sites in nodal PTCL lymphomas as a risk factors or surrogate for outcomes, as OS and PFS in Latin America cohort. Patients (pts) aged ≥18 years with newly diagnosed nodal PTCL-NOS, AITL and ALCL ALK+/ALK-) from GELL (n = 339, 2000-2023, retrospective), TCBP (n = 427, 2015-2022, ambispective). Treatment outcome was determined by OS and PFS. REDcap Platform (by Vanderbilt) was used to collect and store data, whereas statistical analysis the IBM-SPSS v.24. This trial is registered at Clinical trials (NCT03207789). 766 pts [427pts - TCBP and 339 - GELL] diagnosed with nodal PTCL were grouped according to the number of EN: no EN involvement (No EN - 383); one EN involvement (EN1 -168); and 32 (EN2 - 215). Considering all, 61% male; median age 56 y/o; 74% were staged III/IV; 69% IPI 32; 60% was PTCL-NOS, 19% ALCL ALK- and 12% AITL. 61% had B symptoms and 55% elevated LDH. CHOEP was used in 47% and 34% CHOP, and 47% achieved CR after first line; 16% used transplant as consolidation. No EN, EN1 and EN2 were similar regarding clinical characteristics, except, for stage III/IV (58% vs. 79% vs 96%; p < .0001); IPI 32 (58% vs. 59% vs. 99%; p < .0001); ECOG>1 (58% vs. 92% vs. 99%; p < .0001); BMO involvement (16% vs. 24% vs. 63%%; p