Abstract: Objective To explore the efficacy of P-Gemox regimen combined with intensity-modulated radiotherapy for early extranodal NK/T-cell lymphoma（ENKTL）. Methods The clinical data of 73 patients with ENKTL treated in Sichuan Cancer Hospital from March 2012 to October 2017 were analyzed retrospectively. According to the treatment plan，the patients were divided into P-Gemox regimen sandwich radiotherapy group（n=38） and P-Gemox sequential radiotherapy group（n=35），the short-term and long-term clinical effects of the two groups of patients were compared. Results The total effective rate（ORR） of 73 ENKTL patients was 95.9%，the 3-year progression-free survival rate（PFS） was 73.5%，and the 3-year overall survival rate（OS） was 81.9%. The ORR of the P-Gemox regimen sandwich radiotherapy group was 97.4%，and the 3-year PFS and OS were 74.2% and 84.1%，respectively. The P-Gemox regimen sequential radiotherapy group was 94.3%，and the 3-year PFS and OS were 72.6% and 79.2%. There was no significant difference in ORR，PFS，and OS between the two groups（P>0.05）. After adjustment for potential confounders，multivariate Cox regression showed that the PFS of the P-Gemox regimen sandwich radiotherapy group was not inferior to the P-Gemox regimen sequential radiotherapy group（HR=0.617，95%CI：0.353-1.081，P=0.091），while the P-Gemox regimen sandwich radiotherapy group had better OS than the patients of the P-Gemox regimen sequential radiotherapy group（HR=0.556，95%CI：0.314-0.982，P=0.043）. The toxic side effects of chemotherapy in the two groups were mainly Ⅰ-Ⅱ. The P-Gemox regimen sandwich radiotherapy group was more prone to Ⅰ-Ⅱ degree transaminase elevation than the P-Gemox regimen sequential radiotherapy group（P<0.05）. But other toxic side effects，such as hematology and gastrointestinal tract，were not significantly different（P>0.05）. Conclusion The short-term efficacy and PFS of P-Gemox regimen sandwich radiotherapy are similar to those of P-Gemox regimen sequential radiotherapy，while the former can improve the OS of patients compared with the latter.

Key words: Extranodal NK/T-cell lymphoma, Chemotherapy, Radiotherapy, Prognosis