Occupational exposure to vinyl chloride and risk of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common form of cancer that arises from hepatocytes and whose risk may be affected by several known factors, including viruses, alcohol, cigarette smoking, and several genetic conditions. Liver angiosarcoma is a rare cancer that develops from endothelial cells and whose most relevant known risk factor is occupational exposure to vinyl chloride (VC). Since occupational exposure to high levels of VC may still occur, we reviewed the epidemiological and experimental evidence supporting the notion that inhalation exposure to VC is a risk factor for HCC. We find that available epidemiological evidence is based on a dose-risk study with 10 HCC cases and on a partially overlapping study reporting similar results: neither study provided controls for known non-occupational confounders for HCC. Carcinogenesis bioassays of VC inhalation in rodents indicate that angiosarcomas account for nearly all liver tumors induced. Thus, the role of inhalation exposure to VC in HCC risk remains unclear, awaiting further studies and the integration of results from epidemiological studies and animal models.