Rapid detection of superficial head and neck squamous cell carcinoma by topically spraying fluorescent probe targeting dipeptidyl peptidase-IV.

Background: A fluorescent probe glutamylprolyl hydroxymethyl rhodamine green (EP-HMRG), which becomes fluorescent after cleavage by dipeptidyl peptidase-IV (DPP-IV), has been reported to be useful for the detection of esophageal cancer. Thus, we investigated whether head and neck squamous cell carcinoma (HNSCC) can be detected by spraying EP-HMRG.

Methods: Fluorescence imaging of 17 cases of HNSCCs resected using endoscopic or surgical resection was performed ex vivo after spraying EP-HMRG, and then the fluorescence intensity of the tumors and normal mucosa were measured.

Results: Iodine-voiding lesions became fluorescent within a few minutes after the application of EP-HMRG in 12 resected tumors without a history of radiotherapy but this was not observed in the normal mucosa. Fluorescence intensity in tumor lesions was significantly higher than normal lesions. However, 5 other tumors that developed after radiotherapy did not have sufficient contrast against normal mucosa.

Conclusion: Fluorescence imaging with EP-HMRG would be useful for rapid detection of superficial HNSCC without a history of radiotherapy.