Surrogate endpoints shortening the therapeutic evaluation duration for different subgroups of patients with nasopharyngeal carcinoma receiving intensity-modulated radiotherapy: A retrospective analysis of 830 patients stratified by the 8th edition of the UICC/AJCC staging system and plasma Epstein-Barr viral

Purpose: Investigating surrogate endpoints shortening the time of therapeutic evaluation in nasopharyngeal carcinoma (NPC) after radical treatment. Patients and Methods: We retrospectively analyzed 830 patients receiving intensity-modulated radiotherapy (IMRT) from 2008 to 2010 and being stratified by the 8th edition of UICC/AJCC staging system and the plasma Epstein-Barr virus DNA (EBV DNA). The annual rates of overall survival (OS), progression-free survival (PFS), loco-regional recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were sequentially calculated using the life table and compared by the McNemar method. Results: The time of shortening therapeutic evaluation by surrogate endpoints: OS, PFS, LRFS and DMFS could be shortened to 1-year (100% vs 100%, P=1) in patients with stage I; OS, PFS, LRFS and DMFS could be shortened to 3-year (96.9% vs 96.1%, P = 1; 94.6% vs 92.2%, P = 0.125; 96.9% vs 95.3%, P = 0.5) and 4-year (92.2% vs 91.2%, P = 0.125) in stage II; In the high EBV DNA group , OS and DMFS could be shortened to 1-year (100% vs 100%, P = 1;100% vs 100%, P = 0.25) in stage II; OS and PFS could be shortened to 3-year (94.3% vs 91.4%, P = 1;82.9% vs 74.3%, P = 0.25) in stage III; OS could be shortened to 4-year (75% vs 72.7%, P = 1) in stage IVA. Conclusions: The time of therapeutic evaluation could be shortened to <5-year in stages I-II patients. The year of surrogate endpoints could be ahead in stages II-IVA with high EBV DNA.