HPLC DETERMINATION OF SERUM LEVELS OF SOLUBLE P53 ANTIGEN AS A NEW METHOD FOR COLON-CANCER DETECTION, AND ITS CLINICAL IMPLICATION

Previously, we have described a new modification of affinity chromatog raphy columns for isolation of the cytoplasmic, soluble form of tumor- associated antigens (TAA) from the serum of colon cancer patients (Onc ol Rep 2: 679-683, 1995). In this communication, we have shown that th e main proteins of these TAA were p64 and p53. The correlation coeffic ient between each of these proteins and the total amount of TAA or tot al serum protein ranged from 0.55 to 0.93. The serum level of p53 anti gen was shown to be related to the tumorigenicity: the correlation and regression coefficients between the serum level of p53 protein and th e progress in colon cancer were 0.48 and 0.88, respectively, p<0.001. Therefore, the determination of serum concentration of this protein ca n serve as a screening tool for cancer detection. The serum level of p 53 protein ranges between 0.24 to 0.94 mg/ml in patients with non canc er diseases, and between 1.0 to 2.0 mg/ml in patients with polyposis a nd in a high risk group, respectively, increases over 2.0 mg/ml in pri mary colon cancer patients and up to 5.0 mg/ml in cancer patients with metastases. The sensitivity and specificity of our method achieved 92 % and 96%, respectively, and accuracy 88%. The presence of p53 protein in the cytoplasm of cells from patients with non cancer diseases may explain why p53 antigen is presented in their sera. Our method can be useful to detect cancer development either as a primary illness or as a recurrent disorder. It is possible to follow up patients with chroni c diseases and to detect transformation of these diseases into cancer, or to follow up former cancer patients in order to detect as early as possible incidence of recurrent cancer. It should also be emphasized that our method allows the detection of patients with polyposis or tho se of high risk groups who exhibit a tendency to develop colon cancer.