International Session 10 Head and Neck-Basic 3

Head and Neck Squamous cell carcinoma(HNSCC)has a poor prognosis when it recurs after curative treatment.Therefore, early detection of recurrent metastases is important.In this study, we aimed to clarify the usefulness of ctDNA for recurrent metastasis of HNSCC.We collected pretreatment tissue and multiple pre-and posttreatment plasma samples from 20 patients who had undergone curative therapy.Of the pre-treatment plasma, ctDNA was detected in 10 cases, but was not associated with tumor recurrence or stage.Post-treatment ctDNA was detected in post-treatment plasma in 5 cases.Recurrent metastases were found in 7 patients.In 5 of the 7 cases, ctDNA was detected in post-treatment plasma.However, it was not detected in all 13 cases in the recurrence-free metastasis group.There was a significant difference in recurrencefree survival between the groups with and without ctDNA detected in post-treatment plasma(20． 6±7． 7 vs, 9． 6±9． 1 months, respectively; log-rank test, p＜0． 01) .Detection of ctDNA during post-treatment follow-up may be useful in determining treatment efficacy and predicting recurrent metastasis.