Plasma Epstein-Barr virus DNA level strongly predicts survival in metastatic/recurrent nasopharyngeal carcinoma treated with palliative chemotherapy.

BACKGROUND: Plasma Epstein-Barr virus (EBV) DNA is widely used in screening, monitoring, and prediction of relapse in nonmetastatic nasopharyngeal carcinoma (NPC). However, data regarding utility of plasma EBV DNA in metastatic NPC are rare. The current study was to test the prognostic implication of plasma EBV DNA level in metastatic/recurrent NPC patients treated with palliative chemotherapy.

METHODS: Plasma EBV DNA level was measured at baseline and thereafter at the start of each treatment cycle in 127 histologically proven metastatic/recurrent NPC patients treated with palliative chemotherapy. Correlations of pre-treatment and post-treatment plasma EBV DNA levels to survival and response were analyzed.

RESULTS: Patients with a low pre-treatment plasma EBV DNA level (<median) had significantly better survival than those with a high pre-treatment plasma EBV DNA level (≥median). Patients with a post-treatment plasma EBV DNA decline to an undetectable level had better survival and better tumor response compared with those with a sustained detectable post-treatment plasma EBV DNA level. The early decrease of post-treatment plasma EBV DNA to an undetectable level after 1 cycle of chemotherapy was associated with significantly increased survival. Patients with low pre-treatment plasma EBV DNA level and undetectable post-treatment plasma EBV DNA showed a favorable prognosis (5-year overall and progression-free survival of 50.6% and 21.7%, respectively).

CONCLUSIONS: Plasma EBV DNA is of predictive value for prognosis in metastatic/recurrent NPC patients undergoing palliative chemotherapy. The pre-treatment plasma EBV DNA level as well as the early decrease of plasma EBV DNA after chemotherapy enabled easy and early discrimination between patients who will and those who will not benefit from continued treatment.