Bladder cancer is a malignant overgrowth of cells in the bladder. The most common overgrowth is located in the bladder mucosa. The surface of the body’s cavernous organs is usually made up of epithelial cells. For example, the inside of your cheek, stomach, intestines, gallbladder, and also the bladder are all made up of a layer of epithelial cells. Each organ has its own type of epithelial cells. The epithelial cells in the bladder are called uroepithelial cells, and the cancers that arise from them are called uroepithelial cancers, which account for 90-95% of all bladder cancers.
Other less common types of bladder cancer are squamous cell carcinoma and adenocarcinoma. A very rare type of bladder cancer that occurs in children is called rhabdomyosarcoma.
Cancer that spreads to the bladder from elsewhere in the body, called metastatic bladder cancer, is rare and occasionally grows into the bladder from an adjacent organ, such as the prostate, colon, rectum or cervix. All malignancies, including bladder cancer, occur because of changes in the DNA of normal cells.
Chemical exposures can damage the DNA of normal cells, such as smoking, industrial chemicals, chemotherapy, etc. The environmental exposures mentioned above are then called risk factors. Risk factors do not directly cause bladder cancer, just as not every smoker will get bladder cancer. However, in a population-based concept, smokers have an increased risk of developing cancer compared to nonsmokers. Exposure to these factors can increase the chance of DNA damage. When specific DNA that controls cell growth is damaged, normal cells have the potential to become cancerous. Cancer is characterized by an overgrowth of cells that push down and destroy surrounding normal tissue.