A review of experimental models in colorectal carcinogenesis

Colorectal cancer is the leading cause of malignancy of the gastrointestinal tract. A better understanding of the molecular and cellular changes that lead to the disease is necessary to develop early diagnosis and optimal treatment modalities. Rodent models are rapid, reproducible and exhibit an adenoma-carcinoma sequence similar to that found in humans. The objective of this manuscript is to review the most common chemical carcinogens used to induce experimental tumors and the usual methods of evaluation.

Preoperative rectal tumor embolization as an adjunctive tool for bloodless abdominoperineal excision: A case report

BACKGROUND

Abdominoperineal excision (APE)-related hemorrhage can be challenging due to difficult access to pelvic organs and the risk of massive blood loss. The objective of the present study was to demonstrate the use of preoperative embolization (PE) as a strategy for blood preservation in a patient with a large low rectal tumor with a high risk of bleeding, scheduled for APE.

CASE SUMMARY

A 56-year-old man presented to our institution with a one-year history of anal bleeding and rectal tenesmus. The patient was diagnosed with bulky adenocarcinoma limited to the rectum. As the patient refused any clinical treatment, surgery without previous neoadjuvant chemoradiation was indicated. The patient underwent a tumor embolization procedure, two days before surgery performed via the right common femoral artery. The tumor was successfully devascularized and no major bleeding was noted during APE. Postoperative recovery was uneventful and a one-year follow-up showed no signs of recurrence.

CONCLUSION

Therapeutic tumor embolization may play a role in bloodless surgeries and increase surgical and oncologic prognoses. We describe a patient with a bulky low rectal tumor who successfully underwent preoperative embolization and bloodless abdominoperineal resection.

Experimental Model of Rectal Carcinogenesis Induced by N-Methyl-N-Nitrosoguanidine in Mice with Endoscopic Evaluation

Background and purpose: The discovery of chemical substances with carcinogenic properties has allowed the development of several experimental models of colorectal cancer (CRC). Classically, experimental models of CRC in mice have been evaluated through clinical or serial euthanasia. The present study aims to investigate the role of low endoscopy in the analysis of carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Methods: Thirty C57BL6 mice were divided into two groups: a control group with fifteen animals that underwent rectal instillation of saline solution on day 0 and a carcinogen group with fifteen animals that underwent a 100 mg/kg MNNG rectal instillation on day 0. In both groups, low endoscopies were performed on weeks 4 and 8. We used a validated endoscopic scoring system to evaluate the severity of colitis and colorectal tumor. Euthanasia was carried out at week 12. Results: We observed higher inflammation scores (p <0.001) and a higher number of tumors (p <0.05) in the MNNG group than the control group, both at weeks 4 and 8. A worsening of inflammation scores from the first to the second endoscopy was also noticeable in the MNNG group. There were no bowel perforations related to the procedure, and there was one death in the control group. Conclusion: Low endoscopy in experimental animals allows safe macroscopic evaluation of colorectal carcinogenesis without the need for euthanasia.

Infliximab-associated fulminant hepatic failure in ulcerative colitis: a case report

INTRODUCTION

Infliximab, an antibody against tumor necrosis factor alpha, is used to treat inflammatory bowel disease and has well-established efficacy and proven safety. Complications of this treatment are related to immunosuppression and include higher risk of serious infections and malignant neoplasia. Although extremely rare, fulminant liver damage related to infliximab therapy has been reported.

CASE PRESENTATION

We present the case of a 38-year-old Afro-Brazilian woman with refractory ulcerative colitis who was started on infliximab. She had no previous history of liver disease, alcohol abuse, or infection. After the fifth dose of the medication, drug-induced liver injury was diagnosed. Treatment was discontinued but our patient's condition was aggravated by severe cholestasis and grade III/IV encephalopathy, requiring liver transplantation.

CONCLUSION

Drug-induced liver injury is an uncommon complication of infliximab. Current consensus recommends screening for liver dysfunction prior to and during therapy. This case emphasizes the need for vigilance and highlights a rare and potentially lethal complication.

Clinical-Pathological Correlation of KRAS Mutation Status in Metastatic Colorectal Adenocarcinoma

Background

KRAS gene mutations play an important role in the carcinogenesis of colorectal tumors. However, studies that have assessed the association between KRAS gene mutation status and disease characteristics report conflicting results. To assess KRAS gene status (mutated or wild-type) and its association with the clinical, epidemiological, and histopathological features of metastatic colorectal adenocarcinoma as well its association with clinical outcomes.

Methods

Cross-sectional descriptive study in which clinical and histopathological data were collected from the medical records of 65 patients diagnosed with metastatic colorectal adenocarcinoma at the Clinical Oncology Service of the Teaching Hospital of the School of Medicine of Ribeirao Preto, University of Sao Paulo (Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo -HCFMRP-USP) between 2005 and 2012 and analyzed based on their KRAS gene status.

Results

KRAS gene mutations were found in 49.2% of the tumors, and G/A (25.5%) and Gly12Asp (34.37%) were the most frequent mutations. Among the investigated clinical features (gender, ECOG (Eastern Cooperative Oncology Group), histology, degree of cell differentiation, lymph node ratio, primary tumor site, staging, presence of synchronous metastasis, lung metastasis, and liver metastasis), the association between age less than 65 years with KRAS mutation was statistically significant (P = 0.046). KRAS mutation status did not exhibit a significant correlation with the overall survival of the patients (P = 0.078); however, the cases with KRAS mutation exhibited shorter survival. In the multivariate analysis, synchronous metastasis (P = 0.03) and liver metastasis (P = 0.008) behaved as independent factors of poor prognosis relative to the overall survival of the patients.

Conclusion

The KRAS mutation status did not exhibit prognostic value in the investigated sample. Among the older patients (> 65 years old), wild-type KRAS was more frequently observed compared to mutated KRAS.

The epidemiological and clinical features of familial adenomatous polyposis in Ribeirão Preto

Purpose to study 75 familial adenomatous polyposis (FAP) patients treated in a single institution in Ribeirão Preto/SP, from January 1981 to December 2011.

Methods this is a retrospective study and the following data were collected: gender, age, main symptoms, familial history, coexisting malignancies, surgical treatment, surgical morbidity and mortality, factors related to life quality.

Results median age was 29 years. Male-to-female ratio was 1.2:1. Bleeding was the most common symptom (62.6%). Colorectal cancer incidence was 25.5% (n = 19). Extracolonic neoplasia incidence was 8%. Colectomy with ileorectal anastomosis (IRA) was performed in 72% of the patients. Eighteen patients (24%) were submitted to proctocolectomy with “J-pouch” ileoanal anastomosis. In three patients (4%) proctocolectomy with terminal ileostomy was performed. Early and late complication rate were similar (22.7% × 24%). Ileal pouch surgery exhibited tendency to a higher morbidity and mortality but no significance could be found. Overall mortality rate was 7.46%. Malignant neoplasia was the main cause of mortality, accounting for 60% of deaths.

Conclusion FAP is a rare pathology in our country. Genetic counseling and proper screening programs are essential tools to early diagnosis and follow-up. Surgery is the most effective treatment and the best option to prevent malignant neoplasia.