Clinical differences between primary nasopharyngeal NK/T-cell lymphoma and primary nasal cavity NK/T-cell lymphoma with nasopharynx extension

Abstract

Objective: To investigate the clinical and prognostic differences between primary nasopharyngeal natural killer (NK)/T-cell lymphoma (NP NKTCL) and extranodal NK/T-cell lymphoma of the nasal cavity with nasopharynx extension (N-NP NKTCL). Methods: A total of 89 patients with NP NKTCL and 113 patients with N-NP NKTCL from January 2000 to June 2015 were retrospectively analyzed. Clinical and pathological features, treatment responses and prognosis were compared between the two groups. Results: NP NKTCL patients showed similar clinicopathological features with those with N-NP NKTCL, except that the former had a relative low proportion of elevated lactate dehydrogenase (LDH) levels (28.1% vs. 41.6%; P=0.001). Both of two groups presented with high proportion of cervical lymph node involvement (55.1% and 42.5%; P=0.076). The 5-year overall survival (OS) rates in these two groups were 63.2% and 54.6%, respectively, whereas 5-year progress-free survival (PFS) rates were 50.7% and 45.6%, respectively. For the patients with stage Ⅰ and Ⅱ, the 5-year OS and PFS rates in these two groups were 68.8% and 55.7% as well as 55.6% and 47.2%, respectively. These were no statistically significant differences between two groups (all P>0.05). The complete response (CR) rate after initial chemotherapy in NP NKTCL group was 43.8%, which was significant higher than that of 19.6% in N-NP NKTCL group (P=0.006). Additionally, the CR rate after primary radiotherapy was 63.4% and 62.7%, respectively (P=0.629). The NP NKTCL patients with stage Ⅰ and Ⅱ who accepted radiotherapy with or without chemotherapy had similar survival times with chemotherapy alone, showing the 5-year OS rates of 70.5% and 33.3% (P=0.238), as well as the 5-year PFS rates of 56.7% and 33.3%, respectively (P=0.431). Similar results were found in N-NP NKTCL group, the 5-year OS rates for patients with radiotherapy with or without chemotherapy and chemotherapy alone were 57.4% and 33.3% (P=0.246), while the 5-year PFS rates were 49.3% and 16.7% (P=0.177), respectively. Besides, the relapse pattern of NP NKTCL and N-NP NKTCL groups was also similar, mainly involving the distant extra-nodal organs followed by lymph nodes. Conclusion: The patients with N-NP NKTCL and NP NKTCL showed similar clinical and prognostic features, however, the initial response to chemotherapy was different.