Dear Sir,Renal cell carcinoma (RCC) is the most common adult kidney tumour, accounting for around 3% of human malignancies. 1 Its incidence is about 11/100,000 person-years in industrial countries and is increasing as the result of both increases in the prevalence of risk factors and in use of diagnostic imaging procedures. 2-3 Main histological subtypes include clear-cell (75%), papillary (10%) and chromophobe (5%) RCC. Complete surgical resection is considered to be curative for localised RCC but 30% of patients have metastatic disease at diagnosis and RCC is responsible for about 95,000 deaths per year world-wide. 1 Little is known regarding etiological factors of RCC. 2,4 Familial RCC syndromes are estimated at less than 5%; the 2 main conditions are von Hippel-Lindau disease, related to the tumour-suppressor VHL gene, for clear-cell RCC; and hereditary papillary RCC, caused by the c-MET proto-oncogene. 5 Most cases of RCC are thought to be sporadic and many factors are known to increase the risk. Tobacco smoking, obesity (particularly among women), high blood pressure and/or medication prescribed to treat this condition are the main established, although modest, risk factors. 6 -8 A number of reports have also pointed out the potential nephrocarcinogenic effect of occupational exposure to trichloroethylene, gasoline, petroleum products, asbestos, cadmium and iron processing fumes; corresponding epidemiological studies, however, are sometimes controversial. 9 -12 Somatic inactivation of the VHL gene is found in up to 70% of sporadic clear-cell RCC whereas somatic c-MET mutations only occur in 13% of papillary tumours. [13][14][15][16] Prolonged exposure to trichloroethylene during metal machining is associated with clear-cell RCC harbouring a specific pattern of VHL somatic mutations; the identification of this putative mechanism increases the probability for a causative role of trichloroethylene in RCC. 12,17 We recently were made aware of an unexpected number of RCC occurring in a French factory that specialised in vitamin A, vitamin E and methionine synthesis. Between March 1994 and October 2002, 10 cases of RCC were detected in workers from this factory that currently employs 612 men and 116 women. Because of the use of vinyl chloride, a well-documented liver carcinogen, an annual abdominal ultrasonography was progressively introduced in worker medical surveillance in the end of the 1980s. The first RCC was detected by chance in 1994 in a 48-year-old man, who had worked at vitamin A synthesis from 1979 to 1988. To date, 9 further men with RCC have been discovered through systematic ultrasonography and confirmed by CT-scan [ Table I]. Mean age at diagnosis was 52.3 Ϯ 7.8 years and mean diameter of tumour was 2.9 Ϯ 1.0 cm. All patients were successfully operated upon (6 patients underwent a nephrectomy and 4 were treated by conservative surgery) and were free of disease in March 2003. Review of tumour slides identified 7 clear-cell and 3 papillary RCC. The renal tumour was unique in 9 patients and multifoc...