Polycyclic aromatic hydrocarbon exposure in oesophageal tissue and risk of oesophageal squamous cell carcinoma in north-eastern Iran

Objective To evaluate the association between polycyclic aromatic hydrocarbon (PAH) exposure in oesophageal epithelial tissue and oesophageal squamous cell carcinoma (ESCC) case status in an ESCC case-control study in a high-risk population in north-eastern Iran. Methods Tissue microarrays (TMAs) of non-tumoral oesophageal biopsies from patients with biopsy- proven ESCC and gastrointestinal clinic patients with no endoscopic or biopsy evidence of ESCC (control subjects) in a rural region in north-eastern Iran were immunohistochemically stained. Immunohistochemistry was performed using monoclonal antibodies 8E11 and 5D11 raised against benzo[a] pyrene (B[a]P) diol epoxide (BPDE)-I-modi_ed guanosine and BPDE-I-modi_ed DNA, respectively.