How does cancer begin?
Cancer begins with a change in the structure of the deoxyribonucleic acid (DNA) that is found in all human cells. DNA provides cells with a basic set of instructions, such as when to grow and when to reproduce.
A change in the DNA's structure (a genetic mutation) changes these instructions so that the cells carry on growing and reproducing uncontrollably. This produces a lump of tissue that is known as a tumour.
How does cancer spread?
Left untreated, bladder cancer will spread from the lining of the bladder into the surrounding muscles. Once the cancer has reached the muscles it is able to spread to other parts of the body, usually through the lymphatic system.
The lymphatic system is a series of glands (or nodes) that are located throughout your body. It is similar to the blood circulatory system. Lymph glands produce many specialised cells that are needed by your immune system to fight infection.
Once the cancer reaches the lymphatic system, it can spread to any other part of the body, including your bones, blood, and organs. The spread of cancer to other parts of the body is known as metastasis.
Risk factors
Smoking
Smoking is the single biggest risk factor for bladder cancer. This because tobacco contains over 40 different types of carcinogenic (cancer-causing) chemicals.
If you smoke for a prolonged period of time (many years) the carcinogenic chemicals will pass into your urine and will begin to coat the lining of your bladder. This can then cause genetic mutations which lead to the development of bladder cancer.
It is estimated that between 50-65% of bladder cancer cases in men, and between 20-30% of cases in women, are caused by smoking.
Occupational exposure to chemicals
The second biggest risk factor for bladder cancer is occupational exposure to chemicals, which accounts for 10% of all cases.
Chemicals that are known to increase the risk of bladder cancer include:
- aniline dyes,
- 2-Naphthylamine,
- 4-Aminobiphenyl,
- xenylamine, and
- benzidine.
Occupations that have been linked to an increased risk of bladder cancer are manufacturing jobs that involve the following substances:
- rubber,
- dyes,
- textiles,
- plastic, and
- chemicals.
The link between these types of occupations and bladder cancer was discovered during the 1970s and 1980s. Since then, the regulations relating to exposure to cancer-causing chemicals have been made much more rigorous, and many of the above chemicals have been banned. Therefore, in the future, the number of occupation-related cases of bladder cancer should begin to fall.
However, at the moment, the number of occupation-related cases of bladder cancer remains moderately high. This is because it can take up to 25 years after initial exposure to the chemicals before bladder cancer starts to develop.
Other risk factors
Other risk factors for bladder cancer include:
- receiving previous radiotherapy treatments, and
- the long-term use of a catheter (a tube that is used to empty the bladder).
