The efficacy of adjuvant chemotherapy in patients with different midpoint-radiotherapy Epstein-Barr virus DNA plasma loads.

ABSTRACT

OBJECTIVES: This study aimed to evaluate the efficacy of adjuvant chemotherapy (AC) in patients with different midpoint-radiotherapy (mid-RT) Epstein-Barr virus (EBV) DNA plasma loads for locoregionally advanced nasopharyngeal carcinoma (NPC), and to provide decision-making regarding the use of AC. MATERIALS AND METHODS: A total of 675 consecutive patients diagnosed with stage III-IVa NPC were enrolled in this study. All patients underwent concurrent chemoradiotherapy (CCRT), either with or without induction chemotherapy or AC, or a combination of both. The primary endpoint of this study was progression-free survival (PFS). RESULTS: Among the 675 enrolled patients, 248 (36.7 %) received AC and 427 (63.3 %) were only observed after CCRT. In total, 149 (22.1 %) patients had detectable mid-RT EBV DNA levels, whereas 526 (77.9 %) had undetectable mid-RT EBV DNA levels. Patients with detectable mid-RT EBV DNA had worse 5-year PFS than those with undetectable mid-RT EBV DNA (74.8 % vs. 81.9 %, P = 0.045). AC group showed significantly better 5-year PFS than observation in patients with detectable mid-RT EBV DNA (82.8 % vs. 66.8 %; HR, 0.480; 95 % CI 0.250-0.919, P = 0.027). Multivariate analyses demonstrated that the treatment methods (AC vs. observation) were independent prognostic factors for PFS (HR, 0.37; 95 % CI 0.19-0.74, P = 0.005). However, in patients with undetectable mid-RT EBV DNA (5-year PFS HR 0.873, 95 % CI 0.565-1.349, P = 0.52), AC group showed no survival benefit for observation. CONCLUSION: AC could reduce the risk of disease progression compared to observation in patients with detectable mid-RT EBV DNA. Our findings suggest that AC is effective in patients at a high risk of treatment failure.