Relationship between the microvascular patterns observed by magnifying endoscopy with narrow-band imaging and the depth of invasion in superficial pharyngeal squamous cell carcinoma

Background: Prediction of the invasive depth is the objective of endoscopic observation for digestive cancer. In superficial esophageal cancer, a close relationship between microvascular patterns observed by magnifying endoscopy with narrow-band imaging (M-NBI) and pathological depth of invasion is well known. The ability of M-NBI to predict the invasion depth in superficial pharyngeal squamous cell carcinoma (SPSCC) has been seldom evaluated. This study aimed to clarify the relationship between the microvasculature patterns and pathological depth in SPSCC. Methods: SPSCC lesions evaluated with M-NBI followed by endoscopic resection were analyzed between April 2010 and March 2017. Endoscopic images were classified as microvasculature tumor types B1, B2, and B3 according to the Japan Esophageal Society classification. The pathological depth of invasion was described as either squamous cell carcinoma in situ (Tis) or invasive subepithelial cancer, and the tumor thickness of all lesions was examined. Data were analyzed using the unpaired t, χ², or Mann–Whitney U test. Results: Type B1 and type B2/B3 (35/3) microvessels were found in 180 lesions (82%) and 39 (18%), respectively. Of the flat lesions, 115 (83%) were classified as Tis and 23 (17%) as subepithelial cancer. Positive and negative predictive values of the B1 vessels were 77% and 82%, respectively. Additional analysis showed that the positive predictive value of the B1 vessels for the flat-type lesions was 87%; the negative predictive value for the elevated lesions was 93%. Conclusions: Microvascular patterns observed by M-NBI are an important factor in predicting the pathological depth of invasion.