A review of experimental models in colorectal carcinogenesis / Modelos experimentais de carcinogênese colorretal

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.

O câncer colorretal é a principal neoplasia maligna do trato gastrointestinal. Um melhor entendimento dos processos moleculares e celulares é necessário para o desenvolvimento de estratégias que permitam um diagnóstico precoce e um tratamento mais eficaz. Modelos que utilizam roedores são rápidos, reprodutíveis e permitem o estudo da sequencia adenoma-carcinoma de forma similar a encontrada em humanos. O objetivo desse manuscrito é revisar os principais modelos de carcinogênese química e os métodos mais usuais para avaliação dos resultados.

Transanal endoscopic operation for rectal cancer after neoadjuvant therapy

PURPOSE: In this paper we report the oncological outcomes from clinical series of patients with rectal cancer submitted to local excision after neoadjuvant therapy and discuss the indications for local excision in partial clinical responders. METHODS: We analysed a prospective database of 39 patients submitted to a transanal endoscopic operation for rectal cancer after neoadjuvant chemoradiation between 2006 and 2015, comparing clinical and pathological variables, perioperative complications, recurrence rate and overall survival. RESULTS: We obtained 15.4% ypT0, 17.9% ypT1, 35.9% ypT2 and 28.2% ypT3. After a median follow-up of 24 months, tumoral recurrence was observed in 4 patients, one of them with isolated pulmonary metastasis. R0 resection was achieved in 79.5%, and postoperative complications were observed in 30.2% patients and no perioperative mortality occur. Compromise surgical margins do not affect recurrence rate, and 94.9% of patients are alive nowadays. CONCLUSION: Local excision could be associated with low recurrence rate and good overall survival. Short hospitalization time and low level of serious complications observed could be an interesting option for patients who would not tolerate a radical procedure or for those who declined a total mesorectal excision. A strict long-term follow-up must be warranted to detect early tumoral recurrence.

A novel subcutaneous T-shaped bridge device for loop colostomies

PURPOSE: To describe a novel securing device for loop colostomies, developed in our institution and report our 10-year experience. METHODS: The T-shaped support device was used in all patients who required loop colostomy and who were at an increased risk of stoma withdrawal. The device was removed on the fifth postoperative day in all patients. An analysis from a prospective database regarding early postoperative complication, from 209 patients, was conducted between 2003 and 2013. RESULTS: Bleeding, peristomal skin problems, surgical site infection, stomal ischemia/necrosis, stenosis, obstruction, retraction and early withdrawal of the stoma were not noted in all cases. Thirteen patients (6%) reported mild discomfort on the site of the skin suture. Removal of the instrument was fast and easy, with the advantage of keeping the colostomy bag. CONCLUSION: The T-shaped bridge device successfully prevented stoma withdrawal in all subjects. The device was safe and well accepted, with minor complications.