The bladder is a hollow organ of the urinary system. Its main function is to receive and store urine produced by the kidneys prior to evacuation during urination. A healthy bladder can store up to 300 ml of urine before sending signals to the brain to trigger the urge to urinate. The emptying of the bladder requires both the release of the occlusion system (sphincter) located at the outlet of the bladder, and active contraction of muscle fibers located in the bladder wall. Because the kidneys produce urine continuously, any disease of the bladder prevents urine retention, and requires constant urination.
The bladder can be affected by many diseases; however, one of the major diseases of the bladder is cancer. Bladder cancer occurs when, due to some pathological factors, some normal cells of the bladder begin to multiply uncontrollably in the bladder wall. Those disordered cells invade the bladder and destroy normal cells to give rise to malignant tissue; this is called bladder cancer. Depending on the type of cells affected, bladder cancer can be:
- Transitional cell carcinoma (TCC) – also called urothelial cell carcinoma (UCC), TCC is the most common type of bladder cancer and other organs of the urinary system: ureter, urethra, and urachus. Transitional cell carcinoma is accounting for almost 90% of all malign tumors of the bladder. Smoking, unhealthy diet and taking certain medications such as cyclophosphamide and phenacetin can lead to transitional cell carcinoma of the bladder.
- Squamous cell carcinoma – this type of bladder cancer is rare, accounting for about 5% of all bladder tumors. Its occurrence is often linked to infection, irritation or inflammatory diseases of the bladder, especially bilharziasis.
- Adenocarcinoma – this type of bladder cancer develops in a group of cells of the bladder called secretory cells (also called glandular tubes or bladder epithelial cells). Adenocarcinoma of the bladder is a rare type of cancer, accounts for less than 5% of bladder tumors.