Aetiology

No single causative factor is identifiable in the majority of cases. In others, there may be an association with:

• cigarette smoking - by itself, is associated with a 2-fold increased risk. Thought to be due to urinary excretion of inhaled carcinogens. Smoking may act synergistically with other risk factors.
  
  
• occupational exposure to carcinogens widely used in the rubber, cable, textile and printing industries. For example,beta naphthylamine, benzidine, 4-diphenylalinine, and auramine and magenta dyes. Such exposure can be proven in only a small proportion of patients. There may be a latent period of 15-20 years. The bladder is particularly vulnerable as it exposed to urine for longer than other parts of the urinary tract.
  
  
• drugs - e.g. phenacetin, aspirin, cyclophosphamide.
  
  
• fungal toxins in Balkan nephropathy
  
  
• endogenous carcinogens - e.g. nitrosamines, tryptophane metabolites (aminophenols)
  
  
• squamous cell carcinoma is associated with chronic irritation and squamous metaplasia due to bladder stones or schistosomiasis. The latter is the main cause of bladder cancer worldwide.
  
  
• adenocarcinoma may develop in peristent urachal remnants
  
  
• adenocarcinoma or squamous carcinoma may be associated with bladder exstrophy