Retrospective analysis of treatment outcomes for extranodal NK/T-cell lymphoma (ENKL), nasal type, stage I-IIE: single institute experience of combined modality treatment for early localized nasal extranodal NK/T-cell lymphoma (ENKL).

Extranodal natural killer/T-cell lymphoma (ENKL) is a very aggressive disease frequently involving the nasal cavity and upper aerodigestive tract. We retrospectively reviewed the treatment outcomes and treatment-associated complications of the patients with stage I-II early localized ENKL. A total of 24 patients were included. All patients were treated with combined chemoradiotherapy. Three, sixteen, and five patients were initially treated with radiation therapy, chemotherapy, and surgical procedures, respectively. Nine patients underwent hematopoietic stem cell transplantation (HSCT), and four patients administered immunotherapy with pegylated-interferon alpha. The mean observation time was 71.6 months (range, 29.7-183.6 months). Twenty patients achieved complete remission; thus, the overall response rate was 83.3 %. The 5-year overall survival (OS) and relapse-free survival (RFS) rates were 70.3 % and 62.2 %, respectively. In univariate analysis, HSCT was a significant prognostic indicator for OS and RFS. By combining HSCT, the 5-year OS and RFS rates were 100.0 % vs. 52.5 % (p = 0.018) and 88.9 % vs. 45.7 % (p = 0.045), respectively. Also, absence of B symptoms was a good prognostic factor for RFS, the 5-year RFS rate, 75.0 % vs. 25.0 % (p = 0.010), and B symptoms were significant for RFS in multivariate analysis (odds ratio = 7.4, confidence interval = 1.6~34.1, p = 0.011). However, a total of four cases of grade 3 toxicities were reported. Radiation dose range (≤4,500 vs. >4,500 cGy) was significantly correlated with late complications, as more severe complications occurred more frequently with a radiation dose >4,500 cGy (p = 0.026, in multivariate analysis). For more efficient treatment of ENKL, chemotherapy, HSCT, and/or immunotherapy can be combined with radiation therapy to prolong long-term survival and achieve good local control. Also, lower radiation dose could be administered to avoid severe late complications.