The aim of this retrospective study was to evaluate the clinical relevance of serum p53 antibody (S-p53Ab) as a biomarker and to investigate whether its diagnostic value could be improved when combined with other biomarkers of gastric cancer (GC).

Serum samples were obtained preoperatively from 208 patients with histologically-confirmed GC, including 126 stage I patients (60.6%). Levels of S-p53Ab were assessed by a commercial laboratory using an anti-p53 detection kit. The cut-off value for S-p53Ab was 1.3 U/ml.

S-p53Ab was detected in 16.3% (34 of 208) of patients with GC, including 13.6% (22 of 162) of patients with early-stage GC. The positive rates for S-p53Ab, carbohydrate antigen 19-9 (CA19-9), and carcinoembryonic antigen (CEA) of patients with stage I GC were 10.3% (13/126), 2.4% (3/126), and 8.7% (11/126), respectively. Positivity for S-p53Ab was not associated with CA19-9 or CEA positivity (p=0.098 and 0.053, respectively). The positive rate for a diagnosis of GC increased from 16.3% to 29.3% when S-p53-Ab was combined with CEA in this study. We found no significant correlation between the presence of S-p53Ab in GC and overall survival. Conversely, Cox regression analysis revealed that a high level of CA19-9 was an independent prognostic factor for GC in this series (hazard ratio(HR)=3.864; 95% confidence interval(CI)= 1.248-11.959; p=0.019). Kaplan-Meier analyses demonstrated significant differences in survival between patients with elevated levels of both S-p53Ab and CEA and those with elevated levels of only one or neither.

The diagnostic rate of S-p53Ab was better than that of CA19-9 and CEA in patients with stage I GC. Combined detection of S-p53Ab and CEA may improve the diagnostic sensitivity and may permit more accurate stratification of GC patients.