During the past few years, several investigators have devised a number of new biologic tests for the diagnosis of malignant disease. Among these may be mentioned the glycyltryptophan test of Neubauer and Fischer,1 the silk-peptone test of Kuttner and Pulvermacher,2 the amino-acid determination of Barlocco,3 and Woodyatt and Jacque,4 and the incoagulable nitrogen estimation of Morris.5 While these several tests differ in minor details, they are all based on the supposed activity of proteolytic or peptolytic ferments contained within the cancer cells.
While in many instances it has seemed that these measures have been of diagnostic value, in others the results have been directly at variance with the clinical and pathologic findings. As a result, a wide divergence of opinion has arisen as to their clinical value, some commending them highly, others pronouncing them valueless. In the attempts to make these methods more reliable, several
HAMBURGER WW. COMPARATIVE STUDIES IN CANCER AND NORMAL TISSUE FERMENTS. JAMA. 1912;LIX(11):847–851. doi:10.1001/jama.1912.04270090091007