Immunohistochemical localization of glutathione S-transferase-pi in human colorectal polyps

AIM:To investigate the distribution of the placental form of glutathione-S-transferase (GST) in colon polyps in order to evaluate the role of GST-pi in these tissues. METHODS: Sixteen polyp tissues removed at colonoscopy were examined. Tissues were investigated histologically and ultrastructurally. GST-pi expression was also analysed immunohistochemically, using peroxidase anti-peroxidase (PAP) method and immunogold labelling method, for light and electron microscope respectively. RESULTS: All polyp tissues examined were adenoma of low, mild and high-grade dysplasia as shown in the histopathological reports. Nevertheless, the examination of the above specimens with electron microscope revealed that 3 of 9 adenoma of mild dysplasia had ultrastuctural features similar to high-grade dysplasia adenoma. GST-pi was variably expressed in adenoma, with the lowest relative levels occurring in low-gradeadenoma and the highest levels found in high-grade adenoma. GST-pi was located mainly in undifferentiated epithelial cells. GST-pi positive particles were found in the cytoplasm and especially in the nucleus adjacent to the nuclear membrane of these cells. CONCLUSION:The overexpression of GST-pi in mildgrade adenomas with significant subcellular changes and in the majority of high-grade dysplasia adenoma suggests that this might be related to the carcinogenetic proceeding. Immunohistochemical localization of GST-pi in combination with ultrastructural changes indicate that GST-pi might be a sensitive agent for the detection of preneoplastic transformations in adenoma.

Non-compliance in surveillance for patients with previous resection of large (≥ 1 cm) colorectal adenomas

AIM: To assess the extent and reasons of non- compliance in surveillance for patients undergoing polypectomy of large (≥ 1 cm) colorectal adenomas. METHODS: Between 1995 and 2002, colorectal adenomas ≥ 1 cm were diagnosed in 210 patients and subsequently documented at the Erlangen Registry of Colorectal Polyps. One hundred and fi fty-eight patients (75.2%) could be contacted by telephone and agreed to be interviewed. Additionally, records were obtained from the treating physicians. RESULTS: Fifty-four out of 158 patients (34.2%) neglected any surveillance. Reasons for non-compliance included lack of knowledge concerning surveillance intervals (45.8%), no symptoms (29.2%), fear of examination (18.8%) or old age/severe illness (6.3%). In a multivariate analysis, the factors including female gender (P = 0.036) and age > 62 years (P = 0.016) proved to be signif icantly associated with non-compliance in surveillance. CONCLUSION: Efforts to increase compliance in surveillance are of utmost importance. This applies particularly to women’s compliance. Effective strategies for avoiding metachronous colorectal adenoma and cancer should focus on both the improvement in awareness and knowledge of patients and information about physicians for surveillance.

Hypertriglyceridemia is positively correlated with the development of colorectal tubular adenoma in Japanese men

AIM： To determine the real association between serum lipid levels and colonic polyp formation. METHODS： We performed a large scale retrospective study to analyze the correlation between the incidence of colorectal adenoma or carcinoma and the fasting serum levels of total cholesterol （TC） and triglycerides （TG） in patients who underwent total colonoscopy for screening for colon cancer. RESULTS： Both levels were significantly elevated in patients with adenomas as compared with patients without any neoplastic lesion （TC 207.6 ± 29.5 vs 199.5 ±34.3, n= 4883, p〈 0.001; TG 135.0 ± 82.2 vs 108.7± 71.5, n= 4874, p〈 0.001）. The difference was significant in patients with tubular adenoma but not in those with villous or serrated adenoma. Multiple logistic regression analysis including age and sex revealed that TG was an independent correlation factor in male （p〈0.01）, but not in female patients. The level of TG in patients with invasive carcinoma did not show a significant elevation from that in patients with adenoma. These findings suggest that hypertriglyceridemia is an independent risk factor for colonic adenoma in men. CONCLUSION： Although a high level of serum triglyceride does not appear to be mechanically involved in the development of carcinoma, reduction of serum TG and intensive surveillance with total colonoscopy may have benefit in men with hypertriglyceridemia.

Folic acid supplementation inhibits recurrence of colorectal adenomas:A randomized chemoprevention trial

AIM: To determine whether folic acid supplementation will reduce the recurrence of colorectal adenomas, the precursors of colorectal cancer, we performed a double-blind placebo-controlled trial in patients with adenomatous polyps. METHODS: In the current double-blind, placebo-controlled trial at this VA Medical Center, patients with colorectal adenomas were randomly assigned to receive either a daily 5 mg dose of folic acid or a matched identical placebo for 3 years. All polyps were removed at baseline colonoscopy and each patient had a follow up colonoscopy at 3 years. The primary endpoint was a reduction in the number of recurrent adenomas at 3 years. RESULTS: Of 137 subjects, who were eligible after confirmation of polyp histology and run-in period to conform compliance, 94 completed the study; 49 in folic acid group and 45 in placebo group. Recurrence of adenomas at 3-year was compared between the two groups. The mean number of recurrent polyps at 3-year was 0.36 (SD, 0.69) for folic acid treated patients compared to 0.82 (SD, 1.17) for placebo treated subjects, resulting in a 3-fold increase in polyp recurrence in the placebo group. Patients below 70 years of age and those with left-sided colonicadenomas or advanced adenomas responded better to folic acid supplementation. CONCLUSION: High dose folic acid supplementation is associated with a signif icant reduction in the recurrence of colonic adenomas suggesting that folic acid may be an effective chemopreventive agent for colorectal neoplasia.

Gene expression profiling:Canonical molecular changes and clinicopathological features in sporadic colorectal cancers

AIM： To investigate alternative or subordinate pathways involved in colorectal tumorigenesis and tumor growth, possibly determining at-risk populations and predicting responses to treatment. METHODS： Using microarray gene-expression analysis, we analyzed patterns of gene expression relative to canonical molecular changes and clinicopathological features in 84 sporadic colorectal cancer patients, standardized by tumor location. Subsets of differentially expressed genes were confirmed by real-time reverse-transcript polymerase chain reaction （RT-PCR）. RESULTS： The largest number of genes identified as being differentially expressed was by tumor location, and the next largest number by lymphovascular or neural invasion of tumor cells and by mismatch repair （NMR） defects. Amongst biological processes, the immune response was significantly implicated in entire molecular changes observed during colorectal tumorigenesis （P 〈 0.001）. Amongst 47 differentially expressed genes, seven （PISD, NIBP, BAI2, STOML1, MRPL21, MRPL16, and MKKS） were newly found to correlate with tumorigenesis and tumor growth. Most location-associated molecular changes had distinct effects on gene expression, but the effects of the latter were sometimes contradictory. CONCLUSION： We show that several differentially expressed genes were associated with canonical molecular changes in sporadic colorectal cancers, possibly constituting alternative or subordinate pathways of tumorigenesis. As tumor location was the dominant factor influencing differential gene expression, location-specific analysis may identify location-associated pathways and enhance the accuracy of class prediction.

Heterogeneity of colorectal adenomas, the serrated adenoma, and implications for screening and surveillance

Current algorithms for screening and surveillance for colon cancer are valuable, but may be limited by the underlying nature of the targeted neoplastic lesions. Although part of the success of adenoma removal relates to interruption of so-called "adenoma-carcinoma sequence", an alternate serrated pathway to colon cancer may pose difficulties with the ultimate results achieved by traditional colonoscopic methods. The endpoint carcinoma in this unique pathway may be derived from a dysplastic serrated adenoma. These tend to be located primarily in the right colon, especially in females, and are frequently associated with co-existent colon cancer. Unfortunately, however, there are few, if any, other identifiable risk factors, including age or family history of colon polyps or colon cancer. Moreover, this alternate serrated pathway may itself also be quite biologically heterogeneous as reflected in sessile serrated adenomas (SSA) with virtually exclusive molecular signatures defined by the presence of either BRAF or KRAS mutations. Screening algorithms in the future may need to be modified and individualized, depending on new information that likely will emerge on the natural history of these biologically heterogeneous lesions that differs from traditional adenomatous polyps.

Evidence for colorectal sarcomatoid carcinoma arising from tubulovillous adenoma

Sarcomatoid carcinomas of the colorectum are rare tu- mors that display both malignant epithelial and stromal components. Clinically, they are aggressive tumors with early metastasis. Due to their infrequent occurrence, the pathogenesis is poorly understood. We report a case of a 52-year-old woman who presented with a rectal mass and intermittent hematochezia. Superficial biopsies during colonoscopy revealed a tubulovillous adenoma with high-grade dysplasia. Endoscopic ultra- sonography confirmed an invasive nature of the mass, and deeper biopsies revealed the presence of neoplasm with mixed histological components. The surgically- excised specimen demonstrated the presence of poorly differentiated spindle cells underneath the tubulovillous adenoma and an intermediate stage of invasive adeno- carcinoma. Based on the histological appearance and immunohistochemical studies, a diagnosis of sarcoma- toid carcinoma was made. Only nine cases of sarcoma- toid carcinomas of the colorectum have been reported to date. As a result, the terminology and pathogenesis of sarcomatoid carcinoma remain speculative. To the best of our knowledge, this is the first report of co- existence of sarcomatoid carcinoma and invasive ad- enocarcinoma with tubulovillous adenoma; all stages represented within the same tumor. This observation supports the "monoclonal theory" of pathogenesis with an adenoma-sarcoma progression with or without an intermediate stage of carcinoma.

Monoclonal antibodies as therapeutic agents in oncology and antibody gene therapy

Antibodies as therapeutic agents are mostly used in oncology, as illustrated by their applications in lymphoma, breast cancer or colorectal cancer. This review provides a brief historical sketch of the development of monoclonal antibodies for cancer treatment and summarizes the most significant clinical data for the best-established reagents to date. It also discusses strategies to improve the anti-tumor efficacy of antibody therapy, including antibody gene therapy and exploitation of bone marrow derived primary mesenchymal stem cells as the antibody gene transporter.