VALIDATION OF ABSOLUTE LYMPHOCYTE COUNT / REVISED IPI (ALC/R-IPI) SCORE MODEL, AS A PROGNOSTIC INDEX FOR DIFFUSE LARGE-B-CELL LYMPHOMA IN RITUXIMAB ERA

Background. The International prognostic index (IPI), since its publication in 1993, became the primary prognostic tool for patients with DIFFUSE LARGE B-CELL LTMPHOMA (DLBCL). However, the introduction of rituximab (R) has improved patients outcomes and has partially changed the predictive capacity of IPI. In 2007, in the R era, a most accurate prognostic index, termed revised IPI (R-IPI) was proposed by Sehn et al. More recently, Cox et al. showed that absolute lymphocyte count (ALC), at diagnosis has a prognostic impact and it is independent from R-IPI. Thus, they have built-up a score, termed ALC/R-IPI, incorporating both parameters (low risk=ALC≥0.84 109/L and R-IPI very good or good, intermediate risk= ALC<0.84 109/L or R-IPI poor; high risk= ALC<0.84 109/L and R-IPI poor). Aim of our research, utilizing Gruppo Italiano Studio Linfomi (GISL) database is to validate the ALC/R-IPI model on a second larger independent patients data set like the GISL database. Methods and Results. From GISL database we collected data of 831 DLBCL patients, of which 560 treated with chemotherapy alone (1988-2003) and 271 treated with R-containing chemotherapy regimens (2003-2007). We have used the Kaplan-Meier curves, c-Harrell concordance index and the Cox proportional hazard regression to evaluate the ability of ALC/R-IPI to discern patients having good or poor survival. The median age of the 271 cases treated with R was 69 years and 51% were male. At diagnosis, 62% were in stage III/IV, 49% had LDH>UNL, 16% a PS>1, 26% had extranodal sites>1 and 26% presented with ALC<0.84 109/L. The distribution of patients in R-IPI was 7%, 48% and 45% in very good (VG), good (G) and poor (P) groups, respectively. The distribution in ALC/R-IPI was 47%, 42% and 11% in low (L), intermediate (I) and high (H) risk groups, respectively. The OS at 3-years was 88%, 64% and 39% in L, I and H risk groups, with significative differences (p<0.001). The HR were: I vs L = 3.7 (p<0.001); H vs I = 2.1 (p=0.012), while the c-Harrell was = 0.71 (CI95% 0.65-0.76). Conclusions. The ALC/R-IPI showed a good ability to discriminate the prognosis of patients in term of OS in our data base. ALC was confirmed as a specific prognostic factor for DLBCL in R era