Different Clinical Features but Not Outcome in SLL Patients Compared to CLL,

Abstract 3896

Chronic lymphocitytic leukaemia/Small lymphocytic lymphoma (CLL/SLL) is a neoplasm composed of monomorphic small neoplastic B cells that usually co-express CD5 and CD23. The current WHO classification considers CLL/SLL as the same entity being SLL the non-leukemic lymphoma presentation of CLL. The criteria for SLL include the presence of lymphadenopathy with less than 5×10⁹/L peripheral blood B cells. Patients with SLL usually develop PB involvement during the evolution of the disease. The aim of this study was to analyze the main clinico-biological features and outcome of a series of SLL patients and compare them with the CLL patients diagnosed in the same period of time.Patients and methods: we have included 588 patients (353M/ 233F; median age 61 years) diagnosed with CLL or SLL according to the WHO classification criteria in the same period of time.The main clinico-biological features and the outcome were recorded and analysed according to the CLL/SLL diagnosis. Results: five hundred forty-five patients (93%) fulfil the criteria for CLL and 43 patients (7%) for SLL. The main clinico-biological variables according to the CLL/SLL criteria are detailed in the table. No differences were observed in gender distribution, age at diagnosis or ECOG. Patients with SLL had more frequently Binet C stage, low haemoglobin levels and platelet counts. 320 patients eventually received therapy, including purine analogues containing regimens (159 patients), chlorambucil (113), CHOP-like regimens (31), and other therapies (17). Sixty-nine patients received rituximab in combination. SLL patients received more frequently CHOP-like regimens than CLL patients, but this difference did not reach statistical significance. During the follow-up, 58% of the SLL patients eventually developed leukemic presentation, after a median time from diagnosis of 4.6 years (0.2–15 years). Patients with SLL not receiving treatment progressed to PB involvement sooner than treated SLL (median time, 1 year vs 6 year, respectively; p=0.06).Twenty four of the 588 patients eventually developed Richter syndrome, with this proportion being higher in the SLL than in CLL patients (13.1% vs 3.5%; p=0.001). Moreover, the proportion of second neoplasm (excluding non melanoma skin cancer) was higher for SLL patients than for CLL patients. After a median follow-up for surviving patients of 7.4 years (range, 0.1 to 28), 207 patients eventually died with no differences in overall survival between the two groups of patients. In addition, the causes of death were also similar (50% in SLL and 43% in CLL due to disease progression). In conclusion, although the outcome is similar in SLL and CLL groups, SLL patients more frequently had cytopenias as well as higher risk to develop Richter syndrome and second neoplasias. Genetic and other biological studies are warranted to elucidate the particular presentation and features of SLL.