Screenings and clusters: a cancer cluster in a chemical plant

Unrelated to the Navis procedure, in 1986, the plant established an abdominal ultrasound screening programme to detect liver tumours in workers previously exposed to vinyl chloride monomer. Perceived cancer clusters are investigated frequently and approximately 5-15% of these are confirmed by statistical testing. 4 Yet, only a small number of cancer cluster investigations have established a new cause of cancer. 5-7 The observation that vinyl chloride monomer-exposed workers developed angiosarcoma of the liver is particularly relevant to the investigation of the RCC cluster. 8 That discovery, the establishment of the medical screening programme, and its extension to vitamin A synthesis workers facilitated the discovery of the cluster and, possibly, the favourable survival of workers diagnosed with RCC.