The extent of local tumor invasion predicts prognosis in stage IE nasal natural killer/T-cell lymphoma: a novel T staging system for risk stratification.

ABSTRACT

A heterogeneous treatment response and prognosis exists among patients with Ann Arbor stage IE natural killer/T-cell lymphoma (NKTCL), and further risk stratification is required to identify high-risk patients. Here, we assessed the extent of local tumor invasion (LTI) in 185 patients with Ann Arbor stage IE primary nasal NKTCL and proposed a novel four-level T staging system. We found that a more advanced T stage was associated with a significantly lower rate of complete remission (CR) after chemotherapy and a marginally lower rate of CR after radiotherapy. While patients with no LTI (T1) or mild LTI (T2) presented with similar 5-year overall survival (OS; 83.6 % vs. 86.0 %, P = 0.990), those with moderately or highly advanced local disease (T3 or T4) had significantly worse survival (5-year OS was 63.3 % and 35.1 %, respectively). A more advanced T stage (T3 or T4) was an independent prognostic factor for both OS and progression-free survival (PFS) in the Cox regression model. In addition, patients with T3 or T4 disease experienced locoregional failure more frequently than those with T1 or T2 disease, and patients with T4 disease had a significantly higher risk of distant failure. Our data demonstrated that the T staging system, based on the extent of LTI, could serve as an effective clinical parameter for further risk stratification among patients with primary nasal Ann Arbor stage IE NKTCL.