Clinical evaluation of the blood cell carboxypeptidase inhibitor test for malignant neoplasia.

views of these tests have been presented by Hom burger (7) and Huggins (8). With the possible exception of the serum acid phosphatase test for carcinoma of the prostate demonstrated by Gutman and Gutman (6) and the improved methods of cytological examination of fluids developed by Papanicolaou and Trant (10), none of these tests can be considered to be as reliable as a biopsy. Most recently, the tests of Huggins et al. (9), Black et al. (1), and Cliffton (2) have received considerable attention, but these tests, too, have lacked the specificity to be considered diagnostic of cancer. We have demonstrated (5) that in the albino rat the decrease of the blood cell Carboxypeptidase inhibitor (CPI) in response to an implanted tumor is extremely rapid, and that extirpation of the tumor causes an equally rapid recovery of the in hibitor concentration. This sensitive response of a blood component to the presence of a malignant lesion suggests the possibility of using this altered reaction as a blood test for malignant disease in man. A preliminary clinical evaluation of the blood cell CPI test in humans was therefore under taken.