Serum deoxythymidine-5'-triphosphatase (
dTTPase) levels were determined in 71 patients with large bowel
cancers at different clinical stages: 10 patients in Duke's Stage A; 37, in Duke's Stage B; and 24, in Duke's Stage C. The
dTTPase values of patients in Duke's Stage B and C are significantly elevated over normal healthy controls, and a correlation was observed between
tumor stage and
dTTPase activity. While
dTTPase levels rise in patients with increasing
tumor burdens, they decline in patients with undetectable
tumor tissue after radical surgery. Six of 15 courses are documented, illustrating that, after successful operation,
enzyme levels revert to normal. In all patients,
carcinoembryonic antigen levels were determined along with
dTTPase values, and both sets of data were correlated with each other indicating a correlation coefficient of zero. So, if both
dTTPase and
carcinoembryonic antigen are taken into account, the sensitivity of detection of
colorectal carcinomas rises to 66% for all patients and to 92% for patients with a
colorectal carcinoma of Duke's Stage C.