[Diagnostic problems associated with colorectal cancer]

Diagnosis of small superficial colorectal tumors as adenomas or carcinomas has recently become a problem due to conflicting views regarding colonic carcinogenesis. Whether the carcinogenesis follows an adenoma-carcinoma sequence or a de novo cancer is unclear. Colorectal tumors are generally sampled by biopsy, polypectomy and/or colectomy. Biopsy and polypectomy have inherent limitations with regard to histologic diagnosis. Systematic sectioning of the colectomy tissue is essential to ensure the quality of histological diagnosis. The present study examined clinicopathological factors associated with colorectal carcinomas, such as incidence, age, gender, site distribution, and histology, and compared these data with those collected from a multi-institutional registry of large bowel cancer in Japan. Examination of colorectal tumors show that borderline lesions exist between benign and malignant tumors. Histological classification of colorectal intramucosal neoplasia (COIN), which introduces the concept of borderline lesions, was proposed by Kino. We examined the relationships between the COIN classification of tumors and scores of four biological parameters of the tumors: DNA content, Ki-67 positive rate, argyrophilic nucleolar organizer regions and p53 protein overexpression. The scoring system of these four biological parameters correlated well with the COIN classification.