Relationship between bladder cancer incidence, Schistosoma haematobium infection, and geographical region in Zimbabwe.

Bladder cancer is common in Zimbabwe, possibly due to the high prevalence of Schistosoma haematobium infection in some areas. We undertook a correlational study based on retrospective medical record review to see whether the number of bladder cancers could be related to geographical region and prevalence of S. haematobium infection. We also determined patient demographic characteristics and tumour histology. Of 483 patients identified (1984-1987), 69% with available histology had squamous cell carcinomas. The remainder had transitional cell carcinomas. Patients with squamous cell carcinoma were younger than patients with transitional cell carcinomas (50% vs 20% under 50 years old, P less than 0.05) and had a sex ratio of one. There was a positive geographical relationship between S. haematobium prevalence and the incidence of squamous cell carcinoma of the bladder: provinces with high prevalence of S. haematobium had more bladder cancer cases with a predominance of squamous cell carcinoma (r = 0.87, P less than 0.01). These data support a casual relationship between S. haematobium infection and squamous cell carcinoma of the bladder.