PB1801 PRIMARY EXTRA‐NODAL DIFFUSE LARGE B‐CELL LYMPHOMA: A RETROSPECTIVE SINGLE INSTITUTE ANALYSIS ON TREATMENT MODALITIES AND OUTCOME.

Abstract

Background:Extranodal lymphomas comprise around 30% of Non‐Hodgkin lymphomas (NHL) and the majority are diffuse large B‐cell lymphomas (DLBCL). The exact designation of Primary Extranodal NHL (PE‐NHL) is controversial.Aims:The aim of this study is to assess the clinical characteristics of PE‐DLBCL patients focusing on treatment and survival outcome.Methods:Data from patients with PE‐DLBCL treated in the Federico II University of Naples, were retrospectively analyzed. Patients presenting either systemic disease with extranodal involvement or recurrent lymphoma in an extranodal region following prior treatment were excluded. Kaplan‐Meier survival and Log‐Rank test were used for statistical analysis. All cases were reviewed according to the 2016 WHO criteria from our anatomopathologist (MM). PE‐DLBCL was defined as DLBCL histology in a extranodal site and with a FDG‐PETscan completely negative except for lesion uptake. Patients were treated according to the policy of our centre. Complete surgical resection (SR) of the lesion or organ was performed in case of acute complications and in some cases represented the sole treatment action. Treatment modalities were either radiotherapy (RT) or immune‐chemotherapy (R‐CHOP21), alone or in combination. When a Complete Remission (CR) was documented by a negative FDG‐PET/CT and a negative Gastrointestinal (GI) endoscopy for GI lymphomas, patients were followed every 3 months in the first two years, 6 months in the third and one in the subsequent years.Results:From November 2000 to December 2018 fifty‐four patients with PE‐DLBCL were enrolled. Clinical characteristics were reviwed and divided according to primary organ diagnosis (Fig). No patients had B symptoms but some had minor symptoms related to organ involvement. The most frequent comorbidities were viral infections. FDG‐PET was performed and median glucose uptake was calculated divided by type of extranodal diagnosis, some scans were negative because performed after complete SR. No statistically significance difference was found except for bulky disease, more frequent in the GI tract. Patients were divided in 3 cohorts according to the type of treatment received: the first one (61%) were patients treated with 6 cycles of R‐CHOP‐21 with no dose reductions or delays; in the second group patients (31%) received a combined treatment with R‐CHOP‐21, median of 4 cycles (3‐4), following SR; in the last one, (8%) were treated only with SR or RT (Fig). All patients obtained a CR after treatment. During the follow up (median 54 mo) 5 patients relapsed. Three of them received R‐CHOP 21 alone (2 skin PE‐DLBCL and 1 gastric DLBCL), one had a gonad lymphoma treated with SR and the last one had a splenectomy plus R‐CHOP. Relapses involved both extranodal and nodal sites. Median time to relapse was 24mo from the last treatment received. Total PFS was 85%; PFS for R‐CHOP treated patients was 84%, for locally treated patients 75% and for the combined treatment 90% (p = 0.338); OS was 89%.Summary/Conclusion:PE‐DLBCL is a heterogeneous disease with various clinical manifestations at different anatomical sites. Our retrospective analysis showed that PE‐DLBCLs have a better outcome in term of PFS and OS than reported for nodal DLBCLs. Further prospective data analyses are required so as to better elucidate the biology and course of PE‐DLBCL. These data suggest a successful long lasting response to immune‐chemotherapy that prevent patients from undergoing a surgical approach that can be influenced by many complications or radiotherapy approach possibly characterized by critical site‐specific side effects.image