Summary Vinyl chloride (VC) is a know animal and human carcinogen associated with liver angiosarcomas (LAS) and hepatocellular carcinomas (HCC). In VC-associated LAS mutations of the K-ras-2 gene have been reported; however, no data about the prevalence of such mutations in VC associated HCCs are available. Recent data indicate K-ras-2 mutations induce P16 methylation accompanied by inactivation of the p16 gene. The presence of K-ras-2 mutations was analysed in tissue from 18 patients with VC associated HCCs. As a control group, 20 patients with hepatocellular carcinoma due to hepatitis B (n = 7), hepatitis C (n = 5) and alcoholic liver cirrhosis (n = 8) was used. The specific mutations were determined by direct sequencing of codon 12 and 13 of the K-ras-2 gene in carcinomatous and adjacent nonneoplastic liver tissue after microdissection. The status of p16 was evaluated by methylation-specific PCR (MSP), microsatellite analysis, DNA sequencing and immunohistochemical staining. All patients had a documented chronic quantitated exposure to VC (average 8883 ppmy, average duration: 245 months). K-ras-2 mutations were found in 6 of 18 (33%) examined VC-associated HCCs and in 3 cases of adjacent non-neoplastic liver tissue. There were 3 G → A point mutations in the tumour tissue. All 3 mutations found in non-neoplastic liver from VC-exposed patients were also G → A point mutations (codon 12-and codon 13-aspartate mutations). Hypermethylation of the 5′ CpG island of the p16 gene was found in 13 of 18 examined carcinomas (72%). Of 6 cancers with K-ras-2 mutations, 5 specimens also showed methylated p16. Within the control group, K-ras-2 mutation were found in 3 of 20 (15%) examined HCC. p16 methylation occurred in 11 out of 20 (55%) patients. K-ras-2 mutations and p16 methylation are frequent events in VC associated HCCs. We observed a K-ras-2 mutation pattern characteristic of chloroethylene oxide, a carcinogenic metabolite of VC. Our results strongly suggest that K-ras-2 mutations play an important role in the pathogenesis of VC-associated HCC. prove the association of their cancer with VC exposure. As a control group, hepatocellular carcinoma tissue from 20 patients with chronic hepatitis B and C virus infection and alcohol-induced cirrhosis with HCC was used. The presence of K-ras-2 mutations was examined by direct sequencing after microdissection of the tumour nodules. MATERIALS AND METHODS Patients and tissue samplesData were extracted from the German industrial professional association for the chemical industry which is responsible for statutory accident insurance and provides medical and social rehabilitation and financial compensation to persons who incur an industrial injury or occupational disease. According to the German social legislation code VII, compensation for work-related impairment and disability is only possible in cases of a proven association of occupational factor and disease. The criteria for the patients included in this study were a documented chronic quantitated exposure to VC, which leads ...

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BACKGROUND Vinyl chloride (VC) is a known animal and human carcinogen that is associated with liver angiosarcoma and most likely also with hepatocellular carcinoma (HCC) in humans. METHODS The authors examined the presence of p53 gene mutations in 18 HCC specimens from patients with known exposure to VC (median, 8883 parts per million‐years; median duration, 245 months). In all cases, other risk factors for the development of HCC (hepatitis B virus and hepatitis C virus infections, alcohol consumption, and metabolic or autoimmune disorders) were excluded. Three patients had concomitant cirrhosis. The p53 gene was examined by direct sequencing of exons 5–9. RESULTS Mutations of the p53 gene were found in 11 of 18 HCCs examined. The point mutations detected were comprised of five transversions and five transitions. Five of 11 mutations (codons 175, 245, 248, 273, and 282) occurred at CpG sites. Histopathologic liver alterations (mild sinusoidal dilatation, [portal] fibrosis, and centrilobular siderosis) in tumor surrounding nonneoplastic liver confirmed exposure to VC. CONCLUSIONS The results of the current study indicated a relation between VC exposure and the development of HCC. The mutation pattern of p53 with a nearly equal rate of incidence of transitions and transversions and a high rate of incidence of mutations at CpG sites may reflect endogenous mechanisms (e.g., deamination of 5‐methylcytosine) rather than exogenous carcinogens. Cancer 2000;88:1030–36. © 2000 American Cancer Society.