Prognostic Features And Treatment Of Locoregionally Recurrent Extranodal Nasal-type NK/T-Cell Lymphoma

Part I:Prognostic Features and Treatment of Locoregionally Recurrent Extranodal Nasal-type NK/T-Cell LymphomaObjective:To evaluate prognosis in patients with locoregionally recurrent extranodal nasal-type NK/T-cell lymphoma (NKTCL), and to determine the value of salvage radiotherapy.Material and methods:Forty-two patients with NKTCL who developed first locoregional recurrence with (n=13) or without (n=29) systemic failure were reviewed. Retreatment included chemotherapy (n=20), radiotherapy (n=13), and radiotherapy plus chemotherapy (n=9). Fifteen patients were reirradiated for localized recurrent disease.Results:The5-year overall survival (OS) rate after recurrence was40%, with a median survival of26months. The2-year OS rate and median OS were68%and36months for locoregional recurrence only, compared with31%and14months for both locoregional and systemic recurrence, respectively (p=0.034). Subgroup analysis for patients with localized recurrent disease revealed an improved OS with radiotherapy. The2-year and5-year OS rates were77%and69%for radiotherapy, respectively, compared with a2-year OS rate of50%and median OS of16months for chemotherapy alone (p=0.006).Conclusions:Patients with localized recurrence had a better prognosis than those with systemic recurrence. Salvage radiotherapy or reirradiation resulted in a favorable prognosis for patients with localized recurrent disease. Part II:Dose Comparisons for Radiotherapy Plans of Stage I Nasal NK/T-cell LymphomaObjective:To determine the optimal treatment technique for patients with stage I Nasal NK/T-cell Lymphoma.Material and methods:Treatment plans for20patients with stage I Nasal NK/T-cell Lymphoma were developed using8radiotherapy techniques including conventional1field radiotherapy (Con-IF),3dimension conformal radiotherapy (3D-CRT), volumetric modulated arc therapy (VMAT), simple Intensity-modulated radiotherapy (sIMRT),5field intensity modulated radiotherapy (5F-IMRT),7field intensity modulated radiotherapy (7F-IMRT),9field intensity modulated radiotherapy (9F-IMRT), and9field non-coplanar intensity modulated radiotherapy (9F-IMRT-NC). Dose, distribution and delivery efficiency analyses were carried out for each technique.Results:The target coverage of Con-IF was50.3%for patients at limited stage I, while36.9%for extended stage I. PTV Dmax, Dmean, Homogeneous Index (HI), Conformity Index (CI) of3D-CRT were all significantly worse than IMRT. sIMRT achieved similar dose distribution with5F-IMRT in extended stage I patients, with less MU and improved delivery efficiency. VMAT showed inferior PTV Dmax, Dmean in limited stage I patients, and inferior PTV Dmax, Dmean, HI in extended stage I patients, compared to IMRT. But the treatment delivery efficiency of VMAT was much better than the latter. Between all the IMRT techniques,9F-IMRT-NC,9F-IMRT, and7F-IMRT had the optimal dose distribution for limited stage I patients, of which7F-IMRT achieved the best delivery efficiency; the dosimetric quality of9F-IMRT-NC and7F-IMRT were the best for extended stage I patients, while7F-IMRT were more efficient.Conclusions:Con-IF provide inadequate target coverage.3D-CRT were worse than IMRT considering target dose distribution and sparing of normal tissue. VMAT were more efficient than IMRT, with worse dosimetric quality.7F-IMRT is recommended for both limited stage I and extended stage I Nasal NK/T-cell Lymphoma.