Expression of an unusual isozyme of lactate dehydrogenase in the serum of cancer patients and comparison with carcinoembryonic antigen.

Two studies reported here demonstrate a statistically significant association between metastatic cancer and the appearance of the k isozyme of lactate dehydrogenase in serum of affected patients. The first study included 190 coded samples from three types of cancer patients and matched controls; the second included 155 preoperative and 200 postoperative colorectal cancer patients. In the second, plasma carcinoembryonic antigen was compared with serum k isozyme of lactate dehydrogenase as an indicator of the presence of metastatic cancer. This comparison showed that both markers were independently useful for assessing patient status and predicted that a combination of the two should be a better discriminator for the presence of metastases than either marker alone.