Reevaluation of serum p53 antibody as a tumor marker in colorectal cancer patients

We reevaluated the serum p53 antibody (S-p53Ab) ELISA kit, which was approved as a tumor marker of colon cancer in the Japanese Health Insurance System in 2007. S-p53Ab was measured as a tumor marker in 154 colorectal cancer patients, and the results were categorized by clinical and pathological variables. We then compared the positive frequency of S-p53Ab, carcinoembryonic antigen (CEA), and carbohydrate 19-9 (CA19-9). S-p53Ab was positive in 33.1% of the colorectal cancer patients. The positive rate was significantly higher in patients with lymph nodes metastasis (P = 0.025) and lymphatic invasion (P = 0.023). In patients with stage I colorectal cancer, the positive rate of S-p53Ab (23.7%) was significantly higher than that of CEA (5.3%) or CA19-9 (7.9%). The approved kit for S-p53Ab testing was found to be an effective tumor marker of colorectal cancer. The positive rate of S-p53Ab was significantly higher in patients with cancer involvement of the lymphoid tissues. The positive rate of S-p53Ab was higher than that of CEA and CA19-9 in patients with stage I colorectal cancer, suggesting that the S-p53Ab is a useful tumor marker for patients with early-stage disease.