Bladder cancer

The most common urinary bladder cancer by far is the urothelial carcinoma, previously called transitional cell carcinoma (90% of cases). The remaining cases are squamous cell carcinoma and adenocarcinoma.

Urothelial carcinoma can occur anywhere there is urothelium, although it occurs most commonly in the bladder and renal pelvis and more rarely in the ureters and urethra. It's usually asymptomatic in early stages, and the most common presenting symptom is painless haematuria.

Bladder cancer is mostly a disease of older men.

Etiology

Urothelial carcinoma is the second most frequent cancer in smokers, after lung cancer of course. This is because the urothelium is exposed to the toxins in the cigarette smoke after it has been excreted by the kidney. It’s also associated with occupational toxins.

Squamous cell bladder cancer is related to urinary schistosomiasis (a parasite specially in endemic countries like Egypt), chronic bladder irritation and infection.

Pathology

90% of bladder cancer cases are urothelial carcinoma, previously called transitional cell carcinoma.

Classification

The new WHO classification of urothelial carcinoma distinguishes between flat and papillary urothelial lesions:

• Flat lesions
  • Urothelial dysplasia
  • Urothelial carcinoma in situ – flat carcinoma
• Papillary lesions
  • Urothelial papilloma – exophytic growth with normal-looking urothelium
  • Urothelial neoplasm of low malignant potential – similar to papilloma but thicker urothelium
  • Low grade papillary urothelial carcinoma – minimal atypia. retained polarity of cells.
  • High grade papillary urothelial carcinoma – high atypia. loss of polarity.

Less than 10% of low-grade cancers invade, but as many as 80% of high-grade cancers do. Invasion majorly affects the prognosis; 5-year survival is 90% in non-invasive cancer but only 10% in invasive cancer. The degree of which the urothelial tumor has invaded the bladder wall is important in the prognosis. Invasive tumors may extend not only into the bladder wall but to adjacent structures like the prostate, seminal vesicles, ureters and retroperitoneum. Haematogenous dissemination usually involves the liver, lungs and bone marrow.

Polychronotropy

Urothelial carcinoma shows polychronotropy, which means that when one urothelial carcinoma is found it is very likely that other urothelial tumors are present or currently developing at other places of the mucous membrane. Because of this urothelial carcinoma has a high risk of recurrence.

Pathogenesis

Carcinogenesis involves deletions of tumor-suppressor genes on chromosome 9p or 9q. The p16 or p53 genes are commonly involved.

Other histological types

Adenocarcinoma is rare and histologically identical to gastrointestinal adenocarcinomas.

Squamous cell carcinoma is rare and related to chronic inflammation of the bladder.

Diagnosis and evaluation

Haematuria on urine analysis is seen in most cases of bladder cancer.

Patients suspected of having bladder cancer should be referred to cystoscopy. Cystoscopy allows for taking biopsy sample, cytology sample, or even resecting the tumour in its entirety.

CT with contrast is the first choice imaging modality if bladder cancer is suspected based on cystoscopy. It allows for visualisation of the local spreading of the malignancy. Because contrast is filtered by the kidneys, it enters the urinary tract, and a tumour may therefore produce a filling defect. If the tumour has invaded the bladder wall, it will appear thickened on the CT.

Management

Therapy may include:

• BCG – a non-viral strain of mycobacterium tuberculosis which is introduced into the tumor. This activates the immune system which targets the cancer cells.
• TUR – TransUrethral Resection of the tumor
• Radical cystectomy‎