Serum Anti-p53 Antibody Level Measurement
Patient serum p53-Ab levels at approximately 2 weeks after operation and just before starting trial vitamin D supplementation (ie, at randomization), were measured by SRL, Inc (Shinjuku, Tokyo, Japan) using chemiluminescent enzyme immune assay (CLEIA). The lowest measurable serum p53-Ab level is 0.4 U/mL. The study population was divided into 2 subgroups based on serum p53-Ab levels, with patients having levels of 0.4 U/mL or higher designated as p53-Ab (+) and those having levels less than 0.4 U/mL designated as p53-Ab (−).