By using a method of electrophoresis separation, the authors determined the relative values of each one of the lactic dehydrogenase (LDH) isoenzymes in the normal colonic mucosa. In adenocarcinomas, there is a significant rise in the percent of LDH-5. A similar disturbance has been demonstrated in 14 polyps, which confirms the known precancerous condition of these lesions. In the uninvolved mucosa surrounding neoplasm, the authors found that the increase in the relative proportion of "type M" isoenzymes, starting at 2 cm from the edge of the tumor, progressively disappears as the sample are taken farther away from the neoplasm. The authors conclude that these LDH isoenzyme pattern shifts in a normal mucosa could be an early sign of malignancy before the morphologic changes and could also be of great interest in the prediction of cancer relapse in the suture line after surgery.

Segments of gastric mucosa from 32 surgical and biopsy specimens containing gastric carcinoma have been studied to determine the total content of lactate dehydrogenase (LDH). The LDH isoenzyme distribution patterns in tumoral tissues have been compared to that of peritumoral tissue and to the gastric mucosa of a healthy control group. LDH isoenzyme activity in the samples from tumoral tissue was significantly increased. The adjacent peritumoral tissue had a slight increment in the polypeptide M as compared to the distant and normal tissue. This suggests that LDH isoenzyme measurement may prove a valuable addition to histologic study, in the recognition of the tumoral distribution in stomach carcinoma.

By using an original method of electrophoresis separation, the normal relative values of each one of the LDH isoenzymes in the gastric body and antral mucosa were determined. It has been shown in gastric tumors that there is a significance rise in the relative values of "type M" isoenzymes (iso-LDH-4-5). With intestinal metaplasia as well as gastritis, a significant elevation of the relative value of iso-LDH-5 has been demonstrated in the antral mucosa. In 6 benign gastric polyps we found a similar disturbance. This would confirm the known precancerous condition of these lesions. In the normal mucosa of subtotal gastrectomy specimens, 19 patients with antral cancer had 2 types of LDH isoenzyme patterns: one normal and the other with an increase in the relative proportion of "type M" isoenzymes. These LDH isoenzyme pattern shifts in the gastric mucosa could be an early sign of malignancy prior to the morphologic changes.

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