Essential role of radiotherapy in NK/T-cell lymphoma: evidence from a single-center in Mexico

Introduction/Background/Significance: NK/T-cell lymphoma is an aggressive and rare subtype of non-Hodgkin lymphoma

Radiotherapy has represented a key therapeutic modality, especially in early stages of the disease, improving its survival. Some studies have proved that radiotherapy alone can be highly effective inpatients with stages I and II, Initial radiotherapy has shown up to 73.7% complete response rate, significantly higher than that obtained with chemotherapy alone. The combination of radiotherapy with L-asparaginase-based chemotherapy has improved outcomes in patients with localized disease. In regimens such as SMILE followed by radiation therapy have shown 2-year overall survival rates of 100% in some studies.

Materials and Methods/Case Presentation/Objective: We conducted a retrospective, observational and analytic study in patients with NK/T cell lymphoma diagnosis that were attended by the Hospital General de México “Dr. Eduardo Liceaga” between January 2016 to April 2025. The characteristics for inclusion were patients over 18 years with diagnosis confirmed by immunohistochemistry. Those who didn’t count with a complete record or losing follow up were excluded.

Primary Outcome Evaluate the impact of radiotherapy on overall survival in patients with extranodal NK/T-cell lymphoma treated at a single center in Mexico.

Secondary Outcomes: Explore prognostic factors that may influence treatment outcomes in this patient cohort and describe the clinical characteristics of patients diagnosed with extranodal NK/T-cell lymphoma.

Results/Description/Main Outcome Measures: 30 patients with NK/T lymphoma were included. The median age of diagnosis was 36 years (23 to 69 years), and the average was 41.27 years. 17 patients (56.7%) male and 13 (43.3%) women. The anatomic site principally affected was nasal (86.7%). 66.7% of the patients were diagnosed in early stages (I-II) and the rest (33.3%) in stages III-IV. 43.3% of the patients presents ECOG 0 at diagnosis. 96.7% were evaluated by TAC and only 3.3% used PET-CT. The chemotherapy regimen most used was SMILE (63.3%), followed by LVP and L-ASPA-MET-DEX (10% each one). The complete response rate was 36.7%, with 30% of partial response. During the follow up 66.7% of the patients were alive. Patients who didn't receive radiotheraphy OS at 16 months was 16.4%, meanwhile those who did received it, OS at 60 months above 80%. Radiotherapy was associated with less mortality and a higher proportion of censored patients alive

at the end of follow-up. The majority of the mortality occurs during the first year, this is a reflection of the aggressive behavior that it's typical in this kind of lymphoma. The administration of radiotherapy is associated with better outcomes in OS in patients with NK/T cells lymphoma.

Conclusions: The administration of radiotherapy showed to be a fundamental factor in the increase of survival in NK/T cell lymphoma. These results reinforce the need of combined therapies using chemotherapy and radiotherapy in the first line treatment. Also, it is important to highlight the necessity of availability for these therapies in public hospitals, especially in those of high sanitary vulnerability. In conclusion, timely radiotherapy treatment is crucial to improve the survival of patients with NK/T cell lymphoma.