As with many cancers, early detection improves the likelihood of successful treatment. Early symptoms of bladder cancer often involve urinary symptoms, but unfortunately, many of those symptoms are often thought to be caused by a common condition, such as a urinary tract infection. Blood in the urine may be an early indication of cancer, and other symptoms include the need to urinate more frequently and a painful and/or burning sensation during urination.
The bladder is a hollow organ located in the pelvis that functions as part of the urinary system (see Figure 1). It's primary purpose is to store urine before it is eliminated from the body. Urine travels to the bladder from the kidneys - where it's produced - through tubes called ureters. The bladder wall is comprised of four layers: the urothelium, lamina propria, muscularis propria and serosa.
The urothelium, also called the transitional epithelium or mucosa, is the innermost layer of the bladder and is composed of cells called urothelial or transitional cells. The next layer, the lamina propria, is composed of thin connective tissue, blood vessels and nerves. The muscularis propria is thick muscle that makes up the third layer. Lastly, the outermost layer, the serosa, is made up of fatty connective tissue that helps separate the bladder from nearby organs. Together, all of the layers make up a flexible bladder wall.
The bladder can hold approximately two cups of urine. When it’s full, the urge to urinate occurs. When you are ready to urinate, the muscles in the bladder wall contract and force the urine out of the body through a tube called the urethra.
Types of bladder cancer
Most bladder cancers start in the cells that line the surface of the bladder that’s in contact with urine. The most common type of bladder cancer is transitional cell carcinoma – also called urothelial cell carcinoma – and it is divided into two subtypes: papillary and sessile or flat. Papillary tumors grow from the inner lining of the bladder toward the center of the bladder, while sessile tumors grow along the surface of the lining. Both of these types of tumors can be classified as invasive, which are tumors that have grown deep into the bladder wall, or noninvasive, which are tumors that have not penetrated any other layers of the bladder. Other types of bladder cancer include squamous cell carcinoma, adenocarcinoma and small cell carcinoma—all three may be invasive. These subtypes may also be present in one tumor, which can make accurate diagnosis difficult.
When most people receive a diagnosis of any type of cancer, they want to know what may have caused the disease. Bladder cancer most frequently develops in people who are 55 years or older; the average age at the time of a bladder cancer diagnosis is 73 years. Bladder cancer occurs three to four times more often in men than women and is more common in white individuals compared with black individuals. The precise cause of bladder cancer remains unknown, but risk factors linked to the disease include smoking, exposure to certain chemicals (particularly those encountered through work in the chemical industry), diesel exhaust, environmental pollutants, chronic bladder infections, a family history of bladder cancer, previous radiation to the pelvis, or prior use of the chemotherapy drug cyclophosphamide (Cytoxan). It’s important to remember that many people diagnosed with bladder cancer don’t have any of these risk factors, and the disease never develops in many people who do have one or more of these risk factors.