The aim of the study is to investigate plasma miR-21 for a possible
therapeutic effect determination marker in
head and neck squamous cell carcinoma (
HNSCC). Plasma samples are obtained from 86
HNSCC patients and 29 non-
cancer volunteers who had been treated at Mie University Hospital between May 2015 and December 2016, and plasma miR-21 expression was measured using real-time quantitative reverse transcription polymerase chain reaction. In addition, plasma miR-21 level of advanced
HNSCC patients including 22 non-recurrent cases and 11 recurrent cases before and
after treatment was analyzed using a longitudinal design. Plasma miR-21 expression in 86
HNSCC patients was obviously higher than in 29 control patients (P < 0.0001). The area under the curve (AUC) for plasma miR-21 was 0.756 (95% confidence interval: 0.661-0.851). Furthermore, our longitudinal study of plasma miR-21 showed that the expression level of plasma miR-21 was significantly reduced at the time point of 2 months
after treatment in case of no recurrence. On the other hand, plasma miR-21 was not decreased
after treatment in case of 10 patients who had developed recurrences during the follow-up period. This study may provide new insights into the role of plasma miR-21 as a
biomarker for
HNSCC, and plasma miR-21 would be useful for early detection of
tumor recurrence after operation or
chemoradiotherapy.