The early changes in the development of bladder cancer in patients exposed to known industrial carcinogens.

In the Huddersfield district many people have been exposed to industrial carcinogens as a result of their occupation. An exfoliative urine cytology screening programme has been in operation for many years so that patients with the early changes associated with these carcinogens are referred for urological investigation at a very early stage in the disease. A description of the development of urothelial dysplasia, carcinoma in situ and transitional cell carcinoma is presented with particular reference to the urine cytology, histological features of mucosal biopsies and cystoscopic appearances of the bladder. Changes in the collagen fibres in the basement membrane are also described.