Multiple primary malignant tumors involving the large bowel

Catalase activity in erythrocytes from colon and gastric cancer patients. Influence of nickel, lead, mercury, and cadmium

Catalase (CAT) is an enzyme that is involved in antioxidant defense, cell growth, and is possibly associated with tumoral processes. In this paper, the results of experiments designed to determine the influence of metallic carcinogens such as nickel (Ni), lead (Pb), mercury (Hg), and cadmium (Cd), on CAT activity are reported. CAT activity was measured in erythrocytes from three groups: a group of colon cancer patients, a group of gastric cancer patients before clinical treatment, and a control group of healthy blood donors. Concentrations of this enzyme are significantly higher than controls in the colon cancer group, but lower in gastric neoplasia. By generating highly reactive oxygenated species, Ni, Pb, Hg, and Cd alter catalase activity. Solutions of Ni, Cd, and Pb at 0.2 mM concentrations inhibit CAT activity in colon cancer, but increase it in gastric neoplasia. Hg activates CAT in colon cancer, and causes a slightly increased activity in gastric cancer. No complete deactivation of the enzyme was observed.

Multiple primary malignant tumors

Members of colon cancer-prone nonpolyposis families who had multiple primary malignant tumors were analyzed to determine the frequencies, locations, and stages of their cancers, and the duration of their survival. Colon cancers tended to be more proximal, were in a less advanced stage than in the general population, and in a majority of instances were associated with colonic adenomas. The multiple primary malignant tumors were more common in women, and occurred at a younger age than in the general population. Six or more multiple primary malignant tumors occurred in each of 4 patients. All patients survived for more than 10 yr after the diagnosis of the first cancer. Extracolonic cancers were most frequent in the breast and endometrium.

Multifocal carcinoma of the colon

Incidence of multicentric colorectal carcinoma is increasing without any apparent explanation. There are several possible factors in the epidemiology of colon carcinoma and multicentric carcinomas. The so-called polyp-carcinoma sequence has become a matter of increased concern, and ultimately polyp presence should be considered a risk for multiplicity. To reduce the possibility of subsequent new carcinomas, there is a tendency in the management of colon cancer to employ a more radical surgical approach as a prophylactic measure, particularly in patients with multiple primary malignancies or in case of cancer-polyp coexistence.