TP53 and biliary tract neoplasm: Rate of p53 protein overexpression in the 16 patients (surgical resection specimens from 5 patients and biopsy specimens from 11 patients) of the pancreatic cancer group that could be tested was 43.7% (7 patients) and in the 9 patients (surgical resection specimens from 2 patients and biopsy specimens from 7 patients) of the biliary tract cancer group was 55.5% (5 patients).