S100P and invasive carcinoma: Immunohistochemical analysis using primary antibodies against S100P and γH2AX to evaluate neoplastic changes and DNA injury gave highly positive results for the γH2AX and S100P markers in invasive carcinoma, BilIN, and IPNB; but positive γH2AX results and negative S100P results for non‐neoplastic biliary epithelium (Figure 6).16, 17 These results indicate that the carcinogenic process of occupational CCA comprised chronic bile duct injury and DNA damage in almost all the large bile ducts, along with induction of precancerous/preinvasive lesions and development of invasive carcinoma.