Genetic and environmental factors in colorectal carcinogenesis.

The molecular genetic mechanisms of colorectal cancer are among the best understood of any common cancer. Recent research has identified mutated tumor suppressor genes and oncogenes as normal tissue progresses from benign to malignant, and the novel mismatch repair genes involved in a specific form of hereditary colorectal cancer as well as a significant percentage of sporadic cases. This information has led to a better understanding of the inheritance of large bowel cancer, as well as a model of tumorigenesis which proposes a multistep process as colonic epithelial cells progress from their normal state through successive stages of adenoma to malignancy. Exogenous factors such as fiber and fat are important modifiers of inherited risk. Dietary factors may influence the carcinogenic process by modifying intestinal transit time, altering the flow and recycling of bile, or changing the intestinal bacterial flora composition. A number of studies have also suggested the modulation of risk in both hereditary syndromes and sporadic cases with certain micronutrients or medications like nonsteroidal anti-inflammatories.

Paromomycin-associated pancreatitis in HIV-related cryptosporidiosis.

OBJECTIVE: To report a case of pancreatitis related to paromomycin administration. CASE SUMMARY: A 39-year-old man with AIDS developed pancreatitis concurrent with successful treatment of intestinal cryptosporidiosis with paromomycin. The hyperamylasemia resolved with discontinuation of the agent and recurred when paromomycin treatment was reinstituted. DISCUSSION: To our knowledge, this is the first reported case of pancreatitis believed to be induced by paromomycin. Although pancreatitis in HIV-infected patients has multiple causes, the nature of this case suggests the involvement of paromomycin. The mechanism of action is unclear. CONCLUSIONS: Pancreatitis should be considered in the differential diagnosis of abdominal pain in patients who are treated with paromomycin.