Long-term outcomes of 40Gy CCRT with weekly cisplatin and systemic chemotherapy in limited-stage ENKTL.

Radiotherapy (RT) is central in the management of limited-stage extranodal NK/T-cell lymphoma (ENKTL), nasal type. Although international guidelines recommend 50-56 Gy, emerging data suggest that reduced-dose RT with a radiosensitizer may provide comparable control with less toxicity. We evaluated the long-term outcomes of 40 Gy concurrent chemoradiotherapy (CCRT) followed by systemic chemotherapy. We retrospectively analyzed 155 patients newly diagnosed with limited-stage ENKTL treated at Samsung Medical Center between 2000 and 2023. All patients received 40 Gy in RT in 20 fractions with weekly cisplatin (30mg/m2), followed by systemic chemotherapy. Clinical characteristics, treatment response, survival outcomes, and relapse patterns were assessed. The median age was 50 years, and 64.5% were male. Most patients (73.5%) had nasal-type disease, while 20.0% had combined nasal and non-nasal upper aerodigestive tract involvement. At a median follow-up of 73 months, the 5-year PFS and OS rates were 68.0% and 82.2%. Pre-treatment EBV DNA positivity correlated with inferior PFS (p=0.043). Patients receiving CCRT plus chemotherapy had better PFS compared with those receiving CCRT alone (p = 0.004). Relapses occurred in 54 (34.8%) patients, predominantly at extranodal distant sites (21.3%), while the local control rate remained high (86.5%). Secondary malignancies developed in three patients. Median SNOT-22 score was 8, indicating minimal sinonasal symptom burden. A 40 Gy CCRT regimen followed by systemic chemotherapy achieved durable local control and favorable long-term survival in limited-stage ENKTL. The predominance of distant, rather than regional, relapse supports the feasibility of this reduced-dose CCRT strategy combined with systemic therapy.