A retrospective study of histopathological findings in 894 cases of megacolon: what is the relationship between megacolon and colonic cancer?

Abstract

Patients with megaesophagus (ME) have increased prevalence of cancer of the esophagus. In contrast, a higher incidence of colorectal cancer is not observed in patients with megacolon (MC). MC is very common in some regions of Brazil, where it is mainly associated with Chagas disease. We reviewed the pathology records of surgical specimens of all patients submitted for surgical resection of MC in the Hospital das Clínicas of the Faculty of Medicine of Ribeirão Preto (HC-FMRP), from the University of São Paulo. We found that 894 patients were operated from 1952 until 2001 for MC resection. Mucosal ulcers, hyperplasia and chronic inflammation were frequently found, while polyps were uncommon. No patients with MC presented any type of colonic neoplasm. This observation reinforces the hypothesis that MC has a negative association with cancer of the colon. This seems to contradict the traditional concept of carcinogenesis in the colon, since patients with MC presents important chronic constipation that is thought to cause an increase in risk for colon cancer. MC is also associated with other risk factors for cancer of colon, such as hyperplasia, mucosal ulcers and chronic inflammation. In ME these factors lead to a remarkable increase in cancer risk. The study of mucosal cell proliferation in MC may provide new insights and useful information about the role of constipation in colonic carcinogenesis.

Intrinsic denervation of the colon is associated with a decrease of some colonic preneoplastic markers in rats treated with a chemical carcinogen

“…Constipation is a major symptom of megacolon that may be caused by the intrinsic denervation of the viscera. Available human data have shown that intrinsic colonic denervation is protective against the development of colon tumors, but the reasons for this protection remain unknown (2,3). We have reported that colonic denervation due to chemical ablation of myenteric neurons (4) or due to Trypanosoma cruzi infection (5) is associated with a lower incidence of colonic cancer induced by a chemical carcinogen.…”

Trypanosoma cruzi infection and/or administration of the nonsteroidal anti-inflammatory nimesulide increase the number of colonic crypts overexpressing metallothioneins in rat colon carcinogenesis

“…Available clinical data strongly suggest the existence of protection against colon cancer in patients with megacolon due to Chagas' disease, which is caused by T. cruzi (3). However, the mechanisms for this protection against cancer development are not known.…”

Lipoid Pneumonia Complicating Megaesophagus Secondary to Chagas Disease

“…[1][2][3][4] Although its incidence is declining, an impressive number of individuals still suffer from this disease, 1 and it has a wide distribution in Central and South America. It has been reported in all countries in the Americas, except in Canada.…”