The correlation of clinicopathological features and prognosis in extranodal natural killer/T cell lymphoma: a report of 42 cases in the early stage.

This study aimed to explore the clinicopathological features and prognostic correlation of extranodal natural killer (NK)/T cell lymphoma (ENKTCL) in the early stage, screen out the prognostic markers of ENKTCL, and to establish the molecular model of ENKTCL prognosis. A retrospective study was conducted in 88 patients from May 1999 to Dec 2013 in Chinese Academy of Medical Sciences Cancer Hospital, who were diagnosed with ENKTCL according to WHO lymphoid hematopoietic tumor classification (published in 2008). The clinical data and paraffin-embedded tissue blocks were collected. The expressions of CD56, MLH1, PDGFRA, VEGF, PD-L1, PD-1, CyclinD1, p53, and Ki-67 were detected by high-throughput tissue microarray and immunohistochemistry (IHC) staining. The relationship between nine protein expressions and the clinicopathological features and prognosis of patients with ENKTCL were analyzed. The survival time of the 42 patients with complete clinical and follow-up data was 0~153 months. The average survival time was 60.1 months. The survival rates of 1 year, 2 years, and 3 year were 85.7%, 78.6%, and 71.4%, respectively. Single factor survival analysis showed that the increase of serum lactate dehydrogenase (LDH ≥ 240UI/L) before treatment was associated with poor prognosis, and there was a significant difference in survival rate (P = 0.006). Different therapy methods were related with prognosis (P = 0.011); in specifically, radiotherapy alone had the best treatment effect, followed by concurrent chemoradiotherapy, and the worst was chemotherapy alone. But, multivariate statistics indicated that the LDH level and the treatment approach were not independent prognostic factors of ENKTCL. There was no statistical difference between epidemiological factors such as gender, age, and other clinicopathological factors including tumor location, B symptoms, β2-microglobulin levels before treatment, and prognosis. Survival analysis of single factor showed that the positive expression of PDGFRA and PD-L1 was, respectively, related to the poor prognosis of patients with ENKTCL (P = 0.040, 0.007). The patients with Ki-67 overexpression (≥ 50%) had a worse prognosis than those with lower expression (< 50%), and the difference of survival rate between the two groups has statistical significance (P = 0.038). The expression of CD56, MLH1, VEGF, PD-1, CyclinD1, and p53 has no effect on survival rate (P > 0.05). Multivariate survival analysis showed that the expression levels of PDGFRA, PD-L1, and Ki-67 were independent factors in the prognosis of patients with ENKTCL. And the positive expressions of these three proteins were risk factors for prognosis of patients with ENKTCL (PDGFRA: P = 0.045, HR = 8.265, 95% CI: 1.050-65.054; PD-L1: P = 0.005, HR = 9.369, 95% CI: 1.950-45.003; Ki-67: P = 0.023, HR = 3.545, 95% CI: 1.187-10.585). The elevation of serum lactate dehydrogenase (LDH ≥ 240UI/L) before treatment and the treatment approach were associated with poor prognosis, which could be used as adjunct indexes to the prognosis. However, they were not independent factors for the prognosis of patients with ENKTCL. The expressions of PDGFRA, PD-L1, and Ki-67 were independent factors in the prognosis of patients with ENKTCL and these three proteins were risk factors of prognosis. The above markers combined with clinical factors may establish the prognosis model of ENKTCL.