Lactate dehydrogenase isoenzyme patterns in the tumour‐bearing colon

The lactate dehydrogenase (LDH) isoenzyme pattern of the tumour‐bearing colon has been studied in homogenates by disc‐electrophoretic separation. The preponderance of M‐LDH in malignant tissue has been confirmed. It has been shown that the isoenzyme pattern may be altered in the absence of morphological changes. Thus, the metabolic change is not specifically dependent on the existence of tumorous parenchymatous changes as currently recognized by light microscopy. It is suggested that the tumour develops within a tissue where metabolic modifications may precede the stage of morphological malignancy. It appears, therefore, that the alteration of the enzyme pattern might be symptomatic of an established, but very early, neoplastic condition, the microscopic recognition malignancy being a later development.