Extremely malignant kidney tumour, predominantly in patients over forty and commoner in men than women. The tumour itself does not cause discomfort until a late stage, so that secondary tumours produced by metastasis are likely to make their presence felt sooner. Symptoms are fever, weight loss, and finally blood in the urine (haematuria) in 90 per cent of patients. Growth of such tumours can vary considerably, from rapid growth and metastasis to slow growth without symptoms.