Failure patterns and clinical implications in early stage nasal natural killer/T-cell lymphoma treated with primary radiotherapy.

BACKGROUND: This study aimed to evaluate the failure patterns and clinical implications in patients with early stage nasal natural killer (NK)/T-cell lymphoma treated with primary radiotherapy.
METHODS: Two-hundred fourteen patients were included. There were 182 cases of stage I and 32 cases of stage II disease. Patients received radiotherapy alone (n = 96) or radiotherapy and chemotherapy (n = 118). The median dose was 50 grays, and most patients received doxorubicin-based chemotherapy.
RESULTS: The 5-year overall survival (OS) and progression-free survival rates for all patients were 72% and 65%, respectively. Sixty-three patients experienced treatment failure. The 5-year cumulative incidences of locoregional, systemic, and overall failures were 12.0%, 25.5%, and 32.9%, respectively. Stage and paranasal extension were significant predictors for systemic failure. The 5-year cumulative incidence of systemic failure was 22.6% for stage I disease versus 42.7% for stage II disease (P < .001), and 16.9% for limited disease versus 30.4% for paranasal extension (P < .001), respectively. Adding chemotherapy to extended involved-field radiotherapy did not significantly decrease the systemic failure rate nor improve survival. The cumulative incidence of systemic failure and OS rate at 5 years were 24.1% and 74.4% for combined modality therapy compared with 28.5% (P = 0.758) and 69.8% (P = 0.529) for radiotherapy alone. A very low incidence of cervical lymph node or central nervous system relapse was observed.
CONCLUSIONS: Patients with early stage nasal NK/T-cell lymphoma have excellent locoregional control and favorable prognosis with radiotherapy, but patients with stage II disease or paranasal extension are at high risk of systemic failure, emphasizing the importance of integration of optimal radiotherapy with innovative systemic therapy.