Liquid biopsy with plasma Epstein-Barr virus DNA characterizes biological relapse for the prediction of cancer recurrence in non-disseminated nasopharyngeal carcinoma.

PURPOSE

To investigate whether a bounce in plasma Epstein-Barr virus (EBV) DNA during posttreatment surveillance of nasopharyngeal carcinoma (NPC) informs the risk of clinical recurrence and its implication for early therapeutic intervention.

METHODS

950 non-disseminated NPC patients with completed remission in 3 months after treatment were retrospectively screened. Detectable EBV DNA with no evidence of clinical relapse during follow-up was deemed as DNA bounce. The diagnostic and prognostic performance of EBV DNA bounce was assessed for subsequent failures.

RESULTS

Tumor recurrence occurred in 6.6 %, 10.1 % and 65.8 % in the group with persistently negative EBV DNA, single positive test and ≥ 2 positive tests, respectively. EBV DNA bounce over twice was associated with worse disease-free survival (DFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) than the other two groups. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for the prediction of recurrence were 0.56, 0.95, 0.66, 0.93 and 0.90 using two positive tests, which were hence deemed as biological relapse. Serial cutoffs (EBV DNA 1 ≥ 40 copies/ml or EBV DNA 2 ≥100 copies/ml) further defined a high-risk subgroup with an eventual recurrence rate of 77.9 % and 3-year DFS of merely 20.5 %. Prophylactic medical intervention with capecitabine or S1 significantly improved the 3-year DFS when compared to those with observation.

CONCLUSIONS

The earliest two positive tests of EBV DNA represent a biomarker of biological relapse that allows early detection of clinical recurrence in EBV-related NPC. For high-risk biological relapse, preemptive intervention provides potential survival benefits.