Summary:
Clinical data indicate a similar cancer risk in all continent froms of urinary diversion.
The comparison of 40 vesicosigmoidostomy vs rats with and 40 (vs) rats without proximal
colostomy with a similar tumor incidence of 10/40 (25 %) vs 13/40 (32.5 %) support
this theory at least for colonic urinary diversions. N-Nitrosamine excretion in patients
with urinary diversions led to the theory of endogenous nitrosamine formation being
responsible for intestinal tumors in these patients. The ingestion of high dosages
of nitrate (20-100 mg) and the amines proline (Pro/100 mg) and piperazine (Pz/60 mg)
as well as the corresponding nitrosamines NPro (50 μg) and MNPz (50 μg) in vs rats
did not result in increased NPro or MNPz excretion suggesting that the tumor growth
following vs cannot be primarily due to endogenous nitrosation. Animal experiments
show that intestinal anastomoses using ileum have less cancer risk than colonic segments
and that the combination of initially increased proliferation at the vesicocolonic
anastomosis and potentially carcinogenic urine could be important for tumor induction.
In 40 rats we did an ileal interposition between bladder and rectosigmoid (group A)
in comparison to 30 control vs rats (group C) and 40 rats with vs and initial separation
of urine and the anastomosis during the first 12 post-op weeks (group B). In group
A significantly less adenocarcinomas (2/40,5 %) occurred than in group C (9/30, 30
%, p < 0.007) suggesting a prophylactic effect of an ileal interposition following
ureterosigmoidostomy. In group B the incidence was even higher with 16/40 (40 %) showing
that the proliferative stimulus of 2 operations at the anastomosis is more important
for carcinogenesis than urine itself.
Key words:
Tumors following urinary diversion - Epidemiology - Etiology - Tumor prophylaxis
