The Prognosis of Limited Stage Peripheral T-Cell Lymphoma (PTCL): A Population-Based Analysis and Comparison to Diffuse Large B-Cell Lymphoma (DLBCL)
Authors: Savage Kerry Joanne , O'Leary Hilary M , Connors Joseph M , Chhanabhai Mukesh , Campbell Belinda , Sehn Laurie H , Gascoyne Randy D. , Bociek R. Gregory , Armitage James O. , Weisenburger Dennis D. , Vose Julie M. , Bast Martin , Bierman Philip 
Published: October 2019

Abstract
Abstract 4129
Multiple prospective and retrospective studies have demonstrated an inferior prognosis of peripheral T-cell lymphoma (PTCL), with the exception of ALK-positive anaplastic large cell lymphoma (ALCL). However, there is very little information regarding the prognosis of patients with limited stage PTCL and how it compares to diffuse large B-cell lymphoma (DLBCL). Given disease rarity, patients with limited stage PTCL from two institutions, the British Columbia Cancer Agency (BCCA) and the University of Nebraska Medical Center (UNMC) were evaluated.

Methods:
Patients >15 y of age diagnosed with limited stage PTCL between 1981 and 2008, excluding NK/T-cell lymphoma, nasal type and cutaneous ALCL, were identified in the BCCA Lymphoid Cancer Database and from the UNMC. Limited stage PTCL was defined as stage I/IIA, non-bulky (< 10cm) and considered ‘minimal' extent ie. potentially encompassable in a radiotherapy field.

Results:
62 patients with limited stage PTCL were identified (n=35 BCCA and n=27 UNMC). The main histologic subtype was PTCL-NOS (n= 50, 81%) and the remaining patients had ALCL (ALK-negative (neg) ALCL n=7; ALK-positive (pos) ALCL n=5). 14 cases of PTCL-NOS had cutaneous-only disease. Patients had the following clinical characteristics: M:F 1.2:1, median age 52y (18-98y), stage I 68%, 52% extranodal involvement. The majority of patients were treated with anthracycline-based chemotherapy (81%) and over half (53%) received combined modality therapy. The 5-y time to progression (TTP) was similar in irradiated and non-irradiated patients (p=0.52). The outcome of patients with cutaneous-only limited stage PTCL-NOS was excellent with a 5-y TTP and OS of 86% and 92%, respectively. Similarly, patients with ALK-pos ALCL had a very favourable outcome with only 1/5 patients developing relapsed disease and no deaths to date. The 5-y TTP and OS for the remaining cases of PTCL-NOS and ALK-neg ALCL (n=43) were 61% and 67%, respectively. For the whole cohort, there was a more favourable prognosis in patients with a low risk disease by the stage adjusted International Prognostic Index (L-IPI) score at diagnosis (5-y TTP 0 factor 83%, 1 factor 66%, 2 factors 50%, 3 factors 25%, p=.013 and 5-y OS 0 factor 91%, 1 factor 73%, 2 factors 50%, 3 factors 25%, p<.0001). Late relapses (> 5 y) were uncommon, occurring in 2 patients with PTCL-NOS presenting with skin relapses and 1 patient with ALK-neg ALCL with a nodal relapse. The outcome of limited stage PTCL patients was compared to a cohort of BCCA patients diagnosed with limited stage DLBCL who were treated with CHOP-like chemotherapy (without rituximab) and radiotherapy (n=245) (Campbell BA ASCO 2010). In multivariate analysis, excluding cutaneous-only PTCL-NOS and ALK-pos ALCL, there was an inferior TTP in cases with a T-cell phenotype (HR 2.28, p=.003) and a high L-IPI score (HR 1.57, p<.00001). Similarly, the OS was inferior in patients with a T-cell phenotype (HR 1.90, p=.011) and high L-IPI score (HR 1.78, p<.0001). Surprisingly, all of the patients with relapsed (n=4) or refractory (n=3) disease who were able to receive salvage treatment which included stem cell transplant (SCT), (n=7 allogeneic (n=1), autologous (n=6)) are alive and free of disease a median of 7.2 y from the date of transplant (range 1.4 – 16 years). This is in stark contrast to DLBCL patients (n=6), where all but one patient relapsed and died of lymphoma post-transplant.

Conclusion:
Limited stage cutaneous-only PTCL-NOS and ALK-pos ALCL as well as selected patients with PTCL-NOS and ALK-neg ALCL with low risk disease have a favourable prognosis. However, the prognosis remains inferior to limited stage DLBCL. Despite an overall higher risk of relapse, the cure rate is high in limited stage PTCL patients who are able to receive a stem cell transplant as part of their salvage therapy for relapsed or refractory disease.

Disclosures:
No relevant conflicts of interest to declare.