NK/T Cell Versus Peripheral T Cell Lymphoma: Significant Differences in Clinical Characteristics and Survival.

Abstract Background: To compare the clinico-pathologic characteristics and prognosis of Natural Killer/T cell lymphoma (NK/TL) with peripheral T cell lymphoma (PTCL). Methods: A total of 556 resident patients (pts) with lymphoma were treated in the departments of medical oncology and hematology in an Asian institution from 2000 to 2005. Of these pts, 71 (12.8%) had NK/TL or PTCL and were included in this analysis. Pathology was centrally reviewed and classified according to the WHO classification. Results: NK/TL and PTCL comprised of 4.7% (26/556) and 7.9% (45/556) of all cases. Of the PTCL cases, histology was PTCL-NOS in 21, anaplastic large cell in 12 (5 were ALK-1 positive) and angioimmunoblastic T cell in 8 pts. Subcutaneous panniculitis T cell and γ/δ T cell lymphoma accounted for one case each. There were no significant differences between the two groups of pts in terms of sex, performance status, extranodal involvement and LDH level at presentation. However, more patients with NK/TL presented with stage I/II disease (65% vs. 31%, p=0.003). Among pts with NK/TL, 17 (65%) received CHOP-based chemotherapy, 4 received radiation alone and 5 received palliative chemotherapy. In the PTCL group, 39 (87%) received CHOP-based chemotherapy, 2 received radiation alone and 3 received palliative treatment only. Compared to PTCL, NK/TL was associated with a significantly inferior rate of complete remission (27% vs. 58%, p=0.01) and inferior overall survival (5 vs. 28.4 mos, p=0.001). Although age > 60, ECOG ≥ 2, elevated LDH, advanced stage, IPI ≥ 2 and NK/T cell histology were each associated with decreased survival on univariate analysis, only NK/T cell histology and advanced stage were independently associated with decreased survival (see table 1). Conclusions: Contrary to expectation, the incidence of PTCL based on WHO classification in this Asian series is not higher than that reported in Western series. Compared to PTCL, the NK/T subtype is associated with a paricularly inferior prognosis and overrides the prognostic significance of IPI. These data suggest that NK/TL should be considered as a seperate entity and should not be considered together with other subtypes of T cell lymphoma in clinical trials. Table 1. NK/TL vs. PTCL: Univariate and Multivariate Analyses Univariate Analysis Multivariate Analysis Median (yr) P Hazard Ratio 95% CI P Male vs. Female 1.03 vs. Not reached 0.06 0.62 0.28 to 1.40 0.25 Age<60 vs. ≥ 60 2.37 vs. 0.51 0.01 1.41 0.70 to 2.83 0.33 ECOG 0/1 vs. ≥ 2 1.99 vs. 0.36 0.002 1.52 0.63 to 3.65 0.354 LDH normal vs. High Not reached vs. 0.75 0.03 1.29 0.53 to 3.13 0.57 Stage I/II vs. III/IV 1.99 vs. 1.41 0.16 2.91 1.17 to 7.2 0.02 IPI 0/1 vs. ≥ 2 Not Reached vs. 0.42 0.002 2.22 0.82 to 5.99 0.12 PTCL vs. NK/TL 2.37 vs. 0.42 0.001 5.8 2.36 to 14.24 <0.001