Primary nasal natural killer cell lymphoma: long-term treatment outcome and relationship with the International Prognostic Index.

Nasal natural killer (NK) cell lymphoma is rare, so that its optimal therapy, long-term outcome, and prognostic factors are unclear. Data on 52 men and 15 women with well-characterized nasal NK cell lymphomas were analyzed retrospectively to define the impact of primary therapy on remission and long-term outcome and the validity of the International Prognostic Index (IPI). Most (84%) had stage I/II disease with an IPI score of 1 or less (52%). Seven patients received radiotherapy only; 47 patients received anthracycline-containing chemotherapy plus consolidation radiotherapy; and 12 patients received nonanthracycline-containing chemotherapy plus radiotherapy. The overall complete remission (CR) rate was 64.2%; the 20-year overall survival (OS) and disease-free survival (DFS) rates were 37.1% and 33.5%, respectively. Front-line radiotherapy was apparently better than chemotherapy for CR (100% versus 59%, P =.04) and OS (83.3% versus 32.0%, P =.03). Relapses occurred in 4 radiotherapy-treated (all local) and 14 chemotherapy-treated patients (9 local, 4 systemic). Among these, 5 late relapses (4 local, 1 systemic) occurred at 170 months (range, 92-348 months) from CR. The IPI score was of prognostic significance for the whole group (IPI or= 2 for 20-year OS: 57.4% versus 27.6%, P = 0.012), as well as for patients treated with chemotherapy/radiotherapy (IPI or= 2 for CR: 76.7% versus 35.7%, P =.017; and 10-year OS: 63.8% versus 26.8%, P =.003).