Biomonitoring of N-nitroso compounds, nitrite and nitrate in the urine of Egyptian bladder cancer patients with or without Schistosoma haematobium infection

The excretion of nitrate, nitrite, apparent total N-nitroso compounds and volatile nitrosamines was measured in 24 hr urine from 61 Egyptians, divided into 4 groups: controls, Schistosoma haematobium-infected patients and bladder cancer patients with and without a history of schistosomal infection. Urinary nitrate in S. haematobium-infected patients was significantly higher than in the other 3 groups. Nitrite was below the detection limit of the method (≤0.015 μg/mg creatinine) in all but one of the control samples. S. haematobium infection significantly increased urinary nitrite to 0.9 ± 1.16 μg/mg creatinine (mean ± SD, p = 0.001). In both bladder cancer groups, nitrite was about 20 times that in S. haematobium- infected patients without bladder cancer. Excretion of apparent total N- nitroso compounds paralleled that of nitrite. Overall, a good correlation was observed between these 2 variables (r = 0.71, p = 0.0001). N- nitrosodimethylamine was present in all the samples analyzed. S. haematobium infection significantly increased urinary N-nitrosodimethylamine level compared with that of controls (4.02 ± 1.61 and 2.04 ± 2.97 ng/mg creatinine, respectively, p = 0.01). Among cancer patients, N- nitrosodimethylamine was higher than in controls only in those with schistosomal infection. The presence of N-nitroso compounds and N- nitrosodimethylamine in the urine of S. haematobium-infected patients both before and after the development of cancer, and the observation that these compounds also occur in bladder cancer patients with no history of schistosomal infection, suggest that these compounds might have a role not only in the initiation of the carcinogenic process, but also in its progression.