What Causes Bladder Cancer?
Bladder cancer is the tenth most common form of cancer. Each year, it affects over 70,000 Americans and many more worldwide. But what causes bladder cancer, and who is at risk?
The bladder is a muscular, balloon-like organ located in the pelvis. It connects to the kidneys via two long tubes called ureters, which deliver urine to the bladder for storage. When the bladder is full, it releases this urine through another tube called the urethra.
The bladder, ureters, urethra and some other pelvic organs are lined with cells called urothelial cells. Also known as transitional cells, they play a role in immunity and cell-to-cell communication. These cells are the most common site for bladder cancer to develop.
Urothelial (or transitional cell) carcinomas make up the vast majority of bladder cancer cases. Less common types include squamous-cell carcinomas and adenocarcinomas. Small-cell carcinomas and sarcomas are rare.
Now, let’s take a look at some causes of bladder cancer.
1. Tobacco Smoking
Smoking is a leading cause of cancer, including bladder cancer. In fact, smoking cigarettes, cigars, or pipes is thought to contribute to around half of all bladder cancer cases.
This is because toxic chemicals from tobacco smoke pass into the bloodstream from the lungs. The blood then travels to the kidneys to be filtered. The kidneys remove the toxins, producing urine which is then stored by the bladder.
Therefore, the bladder can be exposed to these chemicals for extended periods, especially if urine is stored for a long time.
2. Occupational Exposure
Several industrial chemicals have also been linked with bladder cancer. Most of these have now been banned. However, bladder cancer can take up to 30 years to develop, meaning that occupational exposure still accounts for many cases.
People at risk include those who work, or have worked, in the following industries:
- Leather tanning.
Exhaust fumes have also been linked with bladder cancer, meaning those who work closely with motor vehicles may be at risk. This includes taxi drivers, bus drivers and truck drivers.
Firefighters are also at risk due to being exposed to smoke on a regular basis.
3. Other Environmental Exposure
High levels of arsenic or chlorine in drinking water may also increase the risk of developing bladder cancer. However, this is uncommon in the U.S.
4. Medical Treatments
Some medical treatments can also raise the risk of bladder cancer.
The most common of these are radiation therapy in the pelvic area and chemotherapy. Both are frequently used in the treatment of cancer. However, they can damage healthy cells in the process, thus increasing the risk of other cancers. That said, the benefits usually outweigh the risks.
Another medical treatment that has been linked with bladder cancer is the diabetes drug, pioglitazone. The precise link is unclear.
Finally, long-term indwelling catheters can irritate the bladder lining, leading to chronic inflammation. Inflammation is associated with many different cancers, including bladder cancer.
5. Infection and Inflammation
Irritation and inflammation can also occur because of long-term or repeated urinary tract infections or bladder stones.
Another infection that is linked with bladder cancer is schistosomiasis, also known as bilharzia. It is caused by a freshwater parasite, most commonly found in Africa.
However, it also inhabits several other tropical and subtropical regions, including South America, the Caribbean, Asia and the Middle East.
6. Herbal Medicine
Taking the Chinese herbal medicine aristolochia fangchi can increase the risk of bladder cancer. Other plants in the aristolochia family may also have similar effects.
7. Inherited Conditions
A small number of inherited conditions can increase an individual’s susceptibility to bladder cancer. They include retinoblastoma, Cowden disease and Lynch syndrome.
Furthermore, some people are born with congenital bladder deformities that can increase the risk of cancer later in life.
8. Other Risk Factors
There are several other risk factors for bladder cancer, including:
- Age: most people diagnosed with bladder cancer are over the age of 55.
- Gender: bladder cancer is far more prevalent in males than females.
- Personal or family history of bladder or other pelvic cancers.
It is important to note that not everyone with these risk factors will go on to develop bladder cancer. Equally, it is possible to develop bladder cancer without any of the above risk factors.
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Bladder Cancer Causes and Risk Factors
Cancer develops when cells’ DNA is altered, causing them to behave abnormally. Cancerous cells grow and divide more rapidly than normal, producing a mass of cells called a tumor.
The process can occur due to an inherited or acquired genetic mutation. In bladder cancer, these mutations are usually acquired because of exposure to harmful chemicals. However, in a small proportion of cases, they can be inherited.
Bladder Cancer Symptoms
The most common bladder cancer symptom is blood in the urine. This can manifest as streaky or brown-colored urine.
Other possible symptoms include:
- Frequent need to urinate.
- Needing to urinate urgently.
- Burning or painful urination.
- Lower back or pelvic pain.
- Bone pain.
- Weight loss.
- Leg swelling.
Many of these symptoms have alternate causes. However, anyone experiencing them should seek medical attention as early diagnosis is key to survival.
Bladder Cancer Treatment
Bladder cancer progresses through several stages. The stage at which the cancer is diagnosed will determine the most appropriate treatment method.
Early-stage bladder cancer is sometimes known as non-muscle invasive bladder cancer. At this point, only the cells lining the bladder are affected. These cancerous cells can be removed in a procedure called a transurethral resection of bladder tumor (TURBT). It involves passing a wire loop or laser through the urethra, avoiding the need for open surgery.
If the cancer has spread to the bladder muscle, it is known as muscle-invasive bladder cancer. At this stage, it may be necessary to remove part or all of the bladder, known as a partial or radical cystectomy. The surgeon can form a new bladder using part of the bowel, or make an opening so that urine can be collected outside the body in a urostomy bag.
Both of these procedures are usually combined with chemotherapy, immunotherapy, or targeted therapy to destroy any remaining cancer cells and reduce the risk of it reoccurring.
These treatments may also be useful if the cancer has advanced to the stage where it has spread to other organs. Other treatments for advanced (metastatic) bladder cancer include pain relief and supportive care to improve the patient’s quality of life.