Yoshio Tsubomizu

Cellular and Structural Atypia of the Early Colorectal Cancers

Cellular and structural gland atypia in lesions of early colorectal cancer removed by endoscopic polypectomy in 101 patients were histopathologically studied. The following results were observed. Cellular atypia was frequently found in lesions with a high rate of nuclear polarity loss and multiple nuclear mitoses (99. 0%). The most frequent findings in the glands with structural atypia was intraglandular glands and crowding of neoplastic glands (85. 1%). Most of the appearances of the cellular and structural atypias showed no marked relationship with the sizes of the lesions, depth of invasion and association of adenoma components. Early cancer had both cellular and structural atypia in 95% of the patients and could be diagnosed by conventional histopathological criteria. However five patients with early cancer showed no structural atypia and were diagnosed as having cellular atypia. These cancers were early intramucosal cancer and four lesions were associated with adenoma components 20 mm or less in size. The loss of nuclear polarity and nuclear pleomorphism may be considered more important than nuclear stratification and mitoses in the diagnosis of early cancer.

Is the Histogenesis of 6‐10 mm Early Colorectal Cancer Different from that of Larger Cancers?

Abstract: Out of a total of 466 cases of early colorectal cancer, we analyzed 139 cases with submucosal invasion (sm cancer) according to tumor size, gross appearance, depth and degree of invasion, and the presence of adenoma components. Early colorectal cancers 11 ‐20 mm in diameter were the most common lesion in this group, and the percentage with sm cancer increased with tumor size. More than 70% of relatively small sm cancers, 6‐10 mm in diameter, had moderate or massive submucosal invasion similar to that found in large sm cancers. Only 35% of 6‐10 mm cancers had an adenoma component; the majority (65%) had no adenoma component. In marked contrast, 63% of sm cancers 11 ‐20 mm in diameter had an adenoma component and in sm cancer the percentage of tumors composed solely of cancerous tissue without an adenoma component was low. Similar results were obtained when only protruding type sm cancers, which accounted for the majority of sm cancer cases, were included in the analysis. Therefore, we believe that the protruding type sm cancer 6‐10 mm in diameter is at a stage close to advanced cancer. It is possible that many 6‐10 mm sm cancers have a histogenesis different from that of large sm cancers.