Bilharziasis and bladder cancer: a time trend analysis of 9843 patients.

OBJECTIVE: To explore any changes in bladder carcinoma during 37 years period, in regard to: its frequency, bilharzia association, histological profile and demographic data.

PATIENTS AND METHODS: This is a retrospective study on 9843 patients treated at the National Cancer Institute (NCI), Cairo University, during the years 1970-2007. Three groups were selected: series (A) included 3212 patients during 1970-1974, series (B) 3988 patients during 1985-1989 and series (C) 2643 patients during 2003-2007. For statistical analysis, data of series (A), (B) and (C) were compared to determine the significance of difference (p value 0.005).

RESULTS: A significant decline of the relative frequency of bladder cancer was observed from 27.63% in the old series to 11.7% in the recent series. Bilharzia association dropped from 82.4% to 55.3%. There was a significant rise of transitional cell carcinomas from 16.0% to 65.8%, becoming at present the most common tumor type, with a significant decrease in squamous cell carcinomas from 75.9% to 28.4%. There was an increase in the median age of patients from 47.4 years to 60.5 years and a decrease of male: female (M/F) ratio from 5.4 to 3.3.

CONCLUSIONS: The decline in the relative frequency of bladder cancer is associated with a decline in bilharzia egg positivity in the specimen and is probably related to better control of bilharziasis in the rural population in Egypt. This was accompanied by a change in the histological profile of tumors, with significant predominance of transitional cell carcinoma and an increase in the age of patients, a pattern rather similar to that in western reports.