Tumor induction and prophylaxis following different forms of intestinal urinary diversion in a rat model

Transitional cell carcinoma in orthotopic ileal neobladder

Urothelial carcinoma developing in orthotopic ileal neobladder is an extremely rare entity. Fewer than 10 cases have been reported in the literature describing urothelial carcinoma recurrence in orthotopic ileal neobladder. We report a case of transitional cell carcinoma recurrence in orthotopic ileal neobladder after 11 years of surgery.

[Secondary malignancies in urinary diversions]

In contrast to ureterosigmoidostomy no reliable clinical data exist for tumor risk in different forms of urinary diversion using isolated intestinal segments.In 44 German urological departments, operation frequencies, indications, patient age, and operation dates of the different forms of urinary diversion, operated between 1970 and 2007, could be registered. The secondary tumors up to 2009 were registered as well and related to the numbers of the different forms of urinary diversions resulting in tumor prevalences.In 17,758 urinary diversions 32 secondary tumors occurred. The tumor risk in ureterosigmoidostomy (22-fold) and cystoplasty (13-fold) is significantly higher than in other continent forms of urinary diversion such as neobladders or pouches (p<0.0001). The difference between ureterosigmoidostomy and cystoplasty is not significant, nor is the difference between ileocecal pouches (0.14%) and ileal neobladders (0.05%) (p=0.46). The tumor risk in ileocecal (1.26%) and colonic neobladders (1.43%) is significantly higher (p=0.0001) than in ileal neobladders (0.5%). Of the 16 tumors that occurred following ureterosigmoidostomy, 16 (94%) developed directly at the ureterocolonic borderline in contrast to only 50% following urinary diversions via isolated intestinal segments.From postoperative year 5 regular endoscopic controls of ureterosigmoidostomies, cystoplasties, and orthotopic (ileo-)colonic neobladders are necessary. In ileocecal pouches, regular endoscopy is necessary at least in the presence of symptoms or should be performed routinely at greater intervals. Following neobladders or conduits, only urethroscopies for urethral recurrence are necessary.

Animal models in urinary diversion

We set out to critically assess the value of animal experimentation in urinary diversion through intestinal segments, as some authors question the effectiveness of animal research, criticising the methodological quality, lack of standardization, inadequate reporting and the few systematic reviews in this field. Based on a comprehensive MEDLINE literature search (MeSH database; search terms: urinary diversion, urinary reservoirs, continent, rat, dog, animal models) we retrieved and evaluated all full-length papers published in English, German, French, and Spanish languages from 1966 to 2011 reporting the use of animal models in the setting of urinary diversion. Studies were stratified according to the addressed research question. Within each category species, gender, number of animals, age at procedure, type of diversion, mortality, length of follow-up, experimental procedure and outcome were recorded and tabulated. In all, 159 articles were judged to be relevant and while there are numerous animal models only a few have been used in more than one study. Animals were used for the systematic study of new surgical techniques (93 articles) or metabolic and functional consequences of urinary reconstruction (66 articles). For the latter purpose, the most often used animal is the rat, whereas the dog model is preferred for technical experimentation. In many studies, the validity of the model is at least questionable. Animal experiments have repeatedly been conducted addressing the same question, often with striking discrepancies in outcome. Animal studies were even performed after a surgical technique had been pioneered in humans. The use of animal models in urinary diversion is far from standardized rendering the results less than ideal for comparison across studies. Due to differences in anatomy and physiology, the applicability of findings in animal experiments to clinical urology is limited. Continued effort is needed to optimise the use of animal models in experimental urology.

[Tumors following urinary diversions. Results of a multicenter study]

BACKGROUND

The risk estimation of secondary tumors after different types of urinary diversion with intestinal segments has as yet been possible only for ureterosigmoidostomy.

METHOD

We analyzed the operative records of 44 German clinics for urinary diversions performed from 1970 to 2007 and registered all reported secondary tumors up to 2009.

RESULTS

In 17,758 urinary diversions 32 secondary tumors occurred. The tumor risk in ureterosigmoidostomy (2.58%) and cystoplasty (1.58%) is significantly higher than in other continent forms of urinary diversion (p<0.0001). The risk in orthotopic (ileo)colonic neobladders (1.29%) is significantly higher (p=0.0001) than in ileal neobladders (0.05%). The difference between ileocecal pouches (0.14%) and ileal neobladders is not significant (p=0.46).

CONCLUSION

Ureterosigmoidostomies, cystoplasties, and orthotopic (ileo)colonic neobladders necessitate regular endoscopic evaluation from at least the fifth postoperative year. After ileal neobladders, conduits, and catheterizable ileocecal pouches regular routine endoscopy is not imperative.

SECONDARY MALIGNANCIES IN DIFFERENT FORMS OF URINARY DIVERSION USING ISOLATED GUT

PURPOSE

Tumor development following ureterosigmoidostomy is a worldwide accepted late complication. In contrast, tumor risk in other forms of urinary diversion with the separation of urine and feces is still unclear. We present a complete and detailed analysis of all reported tumors following urinary diversions using isolated gut segments in the literature. We estimated the tumor risk in comparison to ureterosigmoidostomies and to the general population.

MATERIALS AND METHODS

We reviewed the world literature up to April 2003 via MEDLINE for secondary tumors in urinary diversions using isolated intestinal segments.

RESULTS

We found 81 tumor case reports following urinary diversion using isolated intestinal segments. Tumors developed in 18 conduits, 45 cystoplasties, 5 rectal bladders, 3 neobladders, 6 colonic pouches and 4 ileal ureter replacements.

CONCLUSIONS

All urinary diversions using bowel with or without separation of urine and feces carry a significantly higher tumor risk for intestinal tumor development compared to the general population. The tumor spectrum and tumor location in isolated gut segments are different than tumors following ureterosigmoidostomies but the total tumor risk is probably similar. The latency period depends on the initial diagnosis with malignant diseases leading to a shorter induction time. Concerning etiology, many theories exist but the exact mechanism remains unclear. Regular endoscopic control beginning with postoperative year 3 for early detection of secondary malignancies is mandatory.

Tumour formation within intestinal segments transposed to the urinary tract

Patients and their urologists are quite rightly concerned about the possibility of neoplastic change within intestinal segments transposed to the lower urinary tract. This fear arises from the occurrence of latent adenocarcinoma arising from the urocolic anastomosis in approximately 10% of patients who underwent ureterosigmoidostomy in childhood. The present text provides an update of previous reviews and details work published since 1990 on epidemiological, experimental and clinical studies. Consideration of the collected evidence confirms the increased risk of colonic neoplasia following mixing of the faecal and urinary stream by ureterosigmoidostomy or its more recent variants. In contrast, the occurrence of tumours within transposed intestinal segments appears more likely to be related to the underlying urinary tract disease for which the surgery was performed rather than exposure of the intestinal mucosa to urine. This conclusion is, however, based on low level evidence and, despite the reassuring findings, caution is advised until more robust data are available to provide a confident risk assessment.