Akihiko Yamamura

Allelotype analysis of early colorectal cancers with lymph node metastasis

Several studies have indicated that frequent allelic losses in some specific chromosomal regions occur during colorectal cancer (CRC) progression. To clarify the correlation between such allelic losses and metastatic potential, the allelotype of lymph node‐positive early CRCs, which are small but extremely malignant cancers consisting of metastatically competent cells, were investigated. Nineteen paraffin‐embedded specimens of early CRC (pT1 tumors according to TNM classification) with positive lymph nodes were collected. The tumor tissues were examined for loss of heterozygosity (LOH), using microsatellite markers on chromosomes 1p34–36, 8p21–22, 14q32, 18q21 and 22q12–13. The relationship between p53 protein expression and the metastatic status was also investigated by immunohistochemical staining. A group of 20 early CRCs with negative lymph nodes having a similar distribution of macroscopic appearance were used as controls. Among the 19 node‐positive tumors, LOH at 8p21–22 and 18q21 was detected in 11 cases (57.9%) and 17 cases (89.4%), respectively. Allelic losses within these 2 regions in node‐positive tumors were significantly more frequent than that in node‐negative ones (p< 0.01). No significant correlation was found between LOH at 1p34–36, 14q32 or 22q12–13 and lymph node metastasis. p53 protein expression was not significantly associated with lymph node metastasis. Our results suggest that putative tumor suppressor genes, which may be involved in the metastatic process of CRC, are located on chromosomes 8p21–22 and 18q21. Allelic losses in these regions are possible risk factors for lymph node metastasis of early CRC. Int. J. Cancer (Pred. Oncol.) 79:418–423, 1998.

A retrospective study of immunochemical fecal occult blood testing for colorectal cancer detection.

BACKGROUND Colonoscopic examination is the common pathway for positive screening tests detecting colorectal lesions. We evaluated a specific, quantitative high-throughput automatic immunochemical fecal occult blood test (Auto iFOBT) method for colorectal cancer (CRC) screening and to determine its concordance with physician assessments informed by complete colonoscopy, the gold-standard technique for evaluation of the colonic mucosa. METHODS 1200 CRC symptomatic patients were recruited for a retrospective investigation. Colorectal neoplasia were localized by colonoscopy and cancer outcomes were enumerated according to severity. In addition, stool samples were collected and analyzed by Auto iFOBT to derive sensitivity, specificity, and positive predictive value. Qualitative colonoscopy and Auto iFOBT results were correlated, as were cancer severities and quantitative hemoglobin concentrations. RESULTS Ninety-one patients were found positive for CRC; 50 mucosal, 20 submucosal, and 21 advanced. At standard cutoff, sensitivity was 60%, 90%, and 95%, respectively. Specificity and positive predictive value for all neoplasia and cancers were 89.6% and 86.4%, and 60.9% and 33.7%, respectively. Cancer severities could be approximated roughly according to hemoglobin concentrations. CONCLUSIONS Specific qualitative 2-day Auto iFOBT is an accurate tool for the detection of colorectal cancer and therefore provides the basis for a large-scale screening program.

Bone formation in a rectal inflammatory polyp.

Heterotopic bone formation (osseous metaplasia) is rarely detected in the gastrointestinal tract. Most of reported cases are associated with malignant lesions. We herein report a case of osseous metaplasia in a rectal inflammatory polyp and a review of the literature on suggested mechanisms for its aetiology. A 39-year-old man visited our hospital with a chief complaint of melena. Total colonoscopy revealed a slightly reddish subpedunculated polyp, about 12 mm in diameter, in the lower rectum. Endoscopic resection was performed. Histologically, several foci of heterotopic bone formation were found. From the review of the literature, all of the polyps described were larger than 10mm in diameter, 55.6% showed inflammatory changes, and 62.5% were detected in the rectum. Osteogenic stimulation was considered to be a result of the inflammatory process. As our inflammatory polyp was located in the rectum, the pathogenesis could be a reactive change stimulated by the repeated local trauma, or be on a peculiar characteristic of the rectal mucosa itself.