Introduction
The bladder is a muscular bag located in the middle of the pelvis at the lowest point of the abdomen, just behind the pubic bone.
The bladder wall has three basic layers. The inner mucous membrane (mucosa), the circular and longitudinal fiber muscle layer and the outer layer, the peritoneum.
Primary bladder cancer accounts for about seven percent of cancers in men and about three percent of new cancers in women. The rest has spread to the lymph nodes (glands).
Bladder cancer always starts in the mucosa. In the early stages, it is confined to this layer and is characterized as an intracellular carcinoma. For a certain period of time, the cancer only progresses to the inside of the bladder. If detected at this stage, it can be treated with simple local treatments without opening the bladder.
The next stage is when the cancer spreads outwards, deeper into the muscular layer of the bladder. At the same time, the cancer will grow further on the inner surface and spread sideways.
Progressing cancer will grow right through the bladder wall to invade the peritoneum or other tissues on the outside of the bladder. Once the cancer is trapped in the mucosa, it is unlikely to spread to distant lymph nodes or beyond. However, when the bladder wall muscle is invaded, about 13 percent of cancers will also have spread to the lymph nodes. In almost 90 percent of cases, the cancer has spread to the lymph nodes when it breaks through the wall and into the tissue surrounding the bladder.
Symptoms
Bladder cancer is characterized by blood in the urine without pain (hematuria), frequent need to urinate or pus in the urine and burning pain during urination. These symptoms are often indicative of other, less serious conditions, but they should be taken seriously, especially if they occur for the first time in older people.
These symptoms should always be investigated. Sometimes the pain is caused by the retention of blood clots in the urine due to bleeding from the tumor. Pain can also be caused by the cancer spreading to the nerves in that area.
People with advanced bladder cancer may have symptoms caused by the tumor spreading locally or further afield. This can include pain in the lower back, blockage of the urinary tubes (the tubes that carry urine from the kidneys to the bladder) or bone pain from secondary cancer. In rare cases, there may be a mass that can be felt in the bladder area.
Causes
The cause of most bladder cancers is not known for certain, but some causes are known.
These causes include:
- Tobacco tars acquired through smoking and excreted in urine
- Major chemicals such as aniline dyes, beta-naphthylamine and benzidine
- Some chemicals encountered in tire production
- Drugs such as penacetin and cyclophosphamide
- Prolonged bladder inflammation
- – A parasitic disease of African origin, schistosomiasis. Stone formation in the bladder.
Changes in the inner protective surface of the bladder that lead to cancer develop gradually. The most important known causes are alpha and beta naphthylamine, which are excreted in the urine of smokers. Excessive smoking is believed to be a causative factor in half of the cases in men and one third of the cases in women.
Occupational chemical exposure, especially in the tire, oil, leather and paint industries, is likely to be the cause of about thirty percent of cases in men. Artificial sweeteners were once suspected of causing bladder cancer, but several research projects have failed to confirm this suspicion.
In almost all bladder cancers, cancer cells lack part of the long arm of chromosome 9. Many bladder cancers also lack the short arms of chromosomes 11 and 17, and hypothesize that the loss of dominant genes on these chromosomes may be the cause of the cancer.
Diagnosis
Urine can be examined to look for cancer cells.
X-rays taken after injection of a radiopaque dye can show any masses in the bladder. The diagnosis can be confirmed by looking directly into the bladder with a viewing tube called a cystoscope.
Another way to confirm the diagnosis is to use a CT scan or ultrasound. The use of a cystoscope allows a tissue sample to be taken for examination (biopsy) and a positive diagnosis.
Treatment
In about half of people with symptoms of bladder cancer, the tumor is in its early stages and is trapped in the protective lining of the bladder and can be easily treated.
Such advanced cancers can be removed with a laser beam or by cutting the tumor through a cystoscope and burning it with a hot wire (cautery). This procedure is known as transurethral resection of a bladder tumor (TURBT). Some cases are treated by placing anti-cancer drugs directly into the bladder. Anti-cancer drugs can be placed directly into the bladder to try to prevent the cancer from coming back.
When cancer is discovered at a stage when it has already spread deep into the bladder wall, near the lower abdomen or throughout the body, major surgery and/or radiotherapy is necessary. The entire bladder may need to be removed.
Radiotherapy may be used to treat invasive bladder cancer to try and prevent removal of the bladder.
Surgical removal of the bladder is called cystectomy. After a cystectomy, the urinary tubes that carry urine continuously down from the kidneys need to be connected somewhere else. They can be implanted in the colon so that urine is excreted with the feces, or they can be implanted in an artificial bladder made from a separate segment of intestine that excretes fluid through the skin. This type of organ transplantation is called urinary diversion.
