Treatment outcome of patients with advanced stage natural killer/T-cell lymphoma: elucidating the effects of asparaginase and postchemotherapeutic radiotherapy.

The prognosis of advanced stage natural killer/T-cell lymphoma (NKTCL) remains relatively disappointing, and the optimal treatment strategy for this disease has yet to be discovered. Seventy-three patients with Ann Arbor stage III or IV NKTCL were retrospectively reviewed. The treatment efficacies of asparaginase-containing and asparaginase-absent chemotherapy regimens were compared, and the effects of postchemotherapeutic radiotherapy were explored. The overall response rate (ORR) of the asparaginase-containing regimens was marginally higher than that of the asparaginase-absent regimens (56.5 vs 32.6 %, P = 0.057). However, no significant difference was observed in 2-year overall survival (OS) (38.3 vs 22.7 %, P = 0.418) or 2-year progression-free survival (PFS) (25.4 vs 14.9 %, P = 0.134) between the asparaginase-containing and asparaginase-absent groups. Postchemotherapeutic radiotherapy was associated with a significantly prolonged survival (2-year OS 57.5 vs 14.5 %, P < 0.001; 2-year PFS 46.3 vs 8.4 %, P < 0.001) and was an independent predictor of both OS and PFS. Radiotherapy significantly improved the prognosis among the patients who exhibited complete or partial remission after initial chemotherapy (2-year OS 81.5 vs 40.2 %, P = 0.002; 2-year PFS 65.6 vs 23.4 %, P = 0.008) but failed to provide a significant survival advantage among those who experienced stable or progressive disease after initial chemotherapy. In conclusion, the use of asparaginase did not significantly improve survival for the treatment of patients with stage III/IV NKTCL. Postchemotherapeutic radiotherapy provided additional prognostic benefits to patients who responded well to the initial chemotherapy, which requires further validation in future prospective studies using larger sample sizes.