Evaluation of circulating TP53 antigen in the sera of gastric cancer patients: As a tumor marker

This study deals with the detection of serum p53 antigen concentration by enzyme-linked immunosorbent assay as a marker for TP53 gene mutation in gastric cancer patients, correlating it with p53 protein expression detected by immunostaining. The serum concentration of p53 antigen ranged from 0.28 ng/mL to 0.59 ng/mL [average 0.40 ± 0.08 ng/mL, (p < 0.001) compared to the normal control (average 0.19 ± 0.11 ng/mL)]. Positive serum p53 protein concentrations were detected in 29 (36.3%) out of 80 patients, according to adopting a cut-off value for serum p53 protein concentration of 0.42 ng/mL. This corresponded to a value of 2 SD (standard deviations) above the mean value from the healthy controls. Expression of p53 protein was detected in 62.5% (40 of 64) of the nuclei in carcinoma cells from gastric cancer patients. The average serum p53 antigen concentration in the positive immunostained cases was 0.42 ± 0.08 ng/mL, with significant elevation compared with that in the negative immunostained cases (0.36 ± 0.06 ng/mL; p < 0.02). Therefore, serum p53 antigen concentration would be expected to be a useful marker for gastric cancer.