Bladder cancer in various population groups in the greater Durban area of KwaZulu-Natal, South Africa

Objective: To study the incidence of different histological types of bladder cancer in various racial groups living within the same geographical region. Patients and methods: The study included 615 new patients with bladder cancer seen at three provincial hospitals in Durban from January 1980 to January 1990. The patients were classified as Caucasian (white people of European descent), African (indigenous black people), Asian (people originating from the Indian subcontinent) or Coloured (people of mixed race). The bladder tumours were classified according to standard histopathological criteria as transitional cell carcinoma, adenocarcinoma or sarcoma. Mixed tumours consisted of both carcinomatous and sarcomatous or undifferentiated elements. Results: Transitional cell carcinoma constituted 95% of the cancers in Caucasians, compared with only 30% in Africans, whereas squamous cell carcinoma occurred in 53% of the African patients, but in only 2% of the Caucasians. In Asian patients, 75% of the tumours were transitional cell and 18% were squamous cell carcinoma, whereas in Coloureds 82% were transitional cell and 9% squamous cell carcinoma. Undifferentiated carcinoma occurred in 8% of African and only 1% of Caucasian patients, whereas adenocarcinoma, mixed tumours and sarcoma occurred in 9% of African patients and only 2% of Caucasian patients. Ova of Schistosoma haematobium were seen in microscopic sections of the bladder tumour in 85% of the patients with squamous cell carcinoma, in 50% of those with undifferentiated tumours and adenocarcinoma, in 17% of those with mixed tumours or sarcoma, and in only 10% of the patients with transitional cell carcinoma. At presentation, African patients were a mean of >20 years younger than Caucasians. In African patients with squamous cell carcinoma, 90% had stage T3 or T4 disease at presentation, whereas in Caucasian patients with transitional cell carcinoma 76% had stage T1 or T2 disease at presentation. From the study group, it appears that bladder cancer is about six times more common in Caucasians than in Africans. However, the value for Caucasian patients with bladder cancer probably underestimates the true value by about five times, so that bladder cancer in the greater Durban area may be as much as 30 times more common in Caucasians than in Africans. Conclusion: In African patients, endemic Schistosomiasis appears to be related to a high incidence of not only squamous cell carcinoma, but also undifferentiated tumours and adenocarcinoma of the bladder. The effective management of squamous cell carcinoma of the bladder in African patients will depend on the eradication of Schistosomiasis and the early detection of bladder cancer at a stage when it may still be cured by radical treatment.