Endoscopic imaging modalities for diagnosing the invasion depth of superficial esophageal squamous cell carcinoma: a systematic review

Endoscopic diagnosis of the invasion depth of superficial esophageal squamous cell carcinoma (ESCC) is an important determinant of the treatment strategy. The three endoscopic imaging modalities commonly used to predict the invasion depth of superficial ESCC in Japan are non-magnifying endoscopy (non-ME), magnifying endoscopy (ME), and endoscopic ultrasonography (EUS). However, which of these three modalities is most effective remains unclear. We performed a systematic review of the literature to compare the diagnostic accuracy of the three modalities for prediction of the invasion depth of superficial ESCC. We used Medical Subject Heading terms and free keywords to search the PubMed, Cochrane Central, and Ichushi databases to identify direct comparison studies published from January 2000 to August 2020. The results of direct comparison studies were used to compare the diagnostic accuracy of each modality. The primary outcome was defined as the proportion of overdiagnosis of pT1b-SM2/3 cancers, and the main secondary outcome was the proportion of underdiagnosis of pT1b-SM2/3 cancers. Other secondary outcomes were the sensitivity and specificity values of the modalities. Four articles were finally selected for qualitative evaluation. Although ME showed no significant advantages over non-ME in terms of sensitivity and specificity, it had a slightly lower proportion of overdiagnosis. EUS had sensitivity and specificity similar to those of non-ME and ME, but EUS had a higher proportion of overdiagnosis. Non-ME and ME are useful for the diagnosis of cancer invasion depth. EUS may increase overdiagnosis, and caution is required in determining its indications.