Of the 145 patients with SCC, 77 had carcinoma in situ (CIS), 31 had tumor invasion of the basement membrane that was confined to the lamina propria mucosae (m2), 24 had tumor invasion of the muscularis mucosae (m3) and 13 had tumor invasion of the upper submucosal layer (sm). The lesions in the 68 patients with tumor invasion of m2 or deeper (early invasive SCC) were

examined for the presence of a low-grade dysplasia component. For patients with multiple lesions, the lesion with the deepest invasion was examined as the main lesion (the lesion with the largest diameter being examined if the depths of invasion were the same). Characteristics of the patients are shown in Table 1. The depth of cancer invasion and tumor morphology were classified according to the criteria proposed by the Paris endoscopic learn more classification of HKI-272 concentration superficial neoplastic lesions.11 The differences between clinicopathological factors in patients with m2 cancer, m3 cancer and sm cancer were insignificant. EMR was performed with a video-endoscope (Q-230, Q-240; Olympus, Tokyo, Japan). During the period from January

2002 to January 2006, 28 patients were confirmed to have small low-grade dysplasia of the esophagus (< 10 mm in the longest diameter) by endoscopic biopsy during endoscopic screening with iodine staining. The characteristics and natural courses of these 28 lesions were also studied. Characteristics of the patients are shown in Table 2. Morphological features of intraepithelial squamous neoplasia of the esophagus include both architectural and cytological abnormalities.8 The architectural

abnormality is characterized by disorganization of the epithelium and loss of normal cell polarity. Cytologically, the cells exhibit irregular and hyperchromatic nuclei, an increase in nuclear/cytoplasmic ratio and increased mitotic activity. Intraepithelial neoplasia in squamous epithelium of the esophagus is graded as low-grade dysplasia when both architectural and cytological abnormalities are confined to the lower half of the epithelium. The resected specimens were microscopically examined for the presence of a low-grade MCE dysplasia component. If low-grade dysplasia components were observed (≥ 1 high-power field; HPF), the proportions of their areas to overall lesion size were calculated (quantified on longitudinal slices by cutting width). Subsequently, the degrees of architectural and cytological abnormalities of low-grade dysplasia components and those of tumor invasive fronts in the same lesions were studied. The degrees of abnormalities of the 28 small low-grade dysplasia lesions were also studied. They were classified and scored as mild (1 point), moderate (2 points) and severe (3 points). If various degrees of abnormalities were observed, those of the dominant part were recorded. Photomicrographs of the examined specimens are shown in Figures 1–4.