What is Cancer?
"Cancer" is the term we give to a large group of diseases that vary in type and location but have one thing in common: abnormal cells growing out of control.
Under normal circumstances the number and growth of all our cells is a highly controlled mechanism. But when the control signals in one of these cells goes wrong, and its life cycle becomes disturbed, it divides and divides. It continues multiplying uncontrollably, and the result of this accumulation of abnormal cells is a mass of cells called a "tumor". A tumor can be either benign or malignant.
Benign tumors are non-cancerous and are rarely life-threatening. They do not spread (metastasize) to other parts of the body.
Malignant tumors are cancerous and can spread to other parts of the body. When a malignant tumor spreads, the malignant cells break off and travel through the blood lymph system to other places in the body to settle and multiply; or metastasize, resulting in a new tumor called a secondary tumor, or metastasis. The name given to the cancer, however, is reflective of the origin of the cancer, even if it has spread to other areas of the body. For example, if prostate cancer has spread to the liver it is called metastatic prostate cancer. How does it start?
Cancer starts when one normal cell becomes cancerous. This happens when something disrupts the cell DNA, altering the instructional code that monitors the cell’s life cycle. One or more of a variety of risk factors may contribute to the disruption.
The most common cancer risk factors are:
- Genetic predisposition - Certain types of cancer, such as colon and breast cancer, often run in families. It is only the predisposition to cancer that is inherited. Other non-genetic (e.g. environmental) factors must be present for the cancer to develop. Having a family history of cancer does not necessarily mean you will develop cancer, but does however mean that you are at a higher risk. Knowing the risk factors and managing them can help prevent cancer.
- Estrogen exposure (women) - A woman is at increased risk for some gynaecological cancers (e.g. breast or uterine cancer) if her system is exposed to too much estrogens, as this stimulates cell proliferation in these tissues. Factors that contribute to higher estrogen exposure include early menstruation and late menopause. The risk is reduced in women who have had a baby before the age of 35. Other factors that can reduce the risk include regular exercise and a low-fat diet.
- Ionizing radiation - Overexposure to ionizing radiation, such as X rays and nuclear radiation, can cause DNA injury that may lead to cancer.
- Ultraviolet radiation is the radiation from the sun. Ultraviolet B (UVB) rays damage cell DNA and cause 90 percent of all skin cancers. Prevention involves reducing sun exposure, wearing protective clothing and applying a sunscreen with a high SPF (Sun Protection Factor) number.
- Carcinogenic chemicals - Chemical carcinogens such as asbestos, benzene, formaldehyde, and diesel exhaust are dangerous in high concentrations.
- Tobacco smoke - Smoking causes 20-30 percent of all cancer deaths in the world, making tobacco smoke the single most lethal carcinogen. Smoking can cause cancers in the lungs and other organs. The best way to lower the risk of lung and other cancers is to quit smoking, or never start, and to avoid exposure to second-hand smoke if you are a non-smoker.
- Alcohol - People who drink alcohol heavily have a higher risk of mouth, throat, oesophagus, stomach, and liver cancer.
- Carcinogenic foods - There are certain foods that contain carcinogens. Foods that should be limited include salted, pickled, and smoked foods, such as pickles or smoked fish, and meats treated with nitrites. Foods that should be eliminated from the diet include meats that have been charred over a grill, as the charred area is carcinogenic. Taking Vitamin C, either through the diet or by supplementation, may protect against the cancer-causing effects of carcinogenic foods.
- Unhealthy diet - A diet high in saturated fat (especially from red meat) is associated with several different types of cancer, including cancer of the colon, rectum, and prostate gland. Risk can be reduced by reducing fats in the diet, and by eating more soy-based foods, fibber, fruit and vegetables.
- Free radicals are dangerous, highly reactive chemical compounds that can damage DNA and lead to cancer. They can be generated in a number of ways, including oxidation of polyunsaturated fats. Antioxidants (such as Vitamin A and C) taken through supplementation, or a diet high in yellow and orange fruits and vegetables, can reduce the risk.
The cause of the uncontrollable multiplication of abnormal cells, as well as how fast it happens, differs from person to person. Many people overcome the disease, and many living with the disease live fulfilled lives for many years. If you or someone close has been diagnosed with cancer, you may be interested to learn more about the cancer and/or what treatments to expect.
There are a number of treatment options available for cancer. Treatments plans are developed depending on the type of cancer, its location, the extent of the cancer and the stage at which it is diagnosed, and the health and well-being of the patient. Treatment may be one or more of several different therapies.* Chemotherapy is the use of anti-cancer of drugs. Anti-cancer drugs destroy cancer cells by stopping growth or multiplication at some point in their life cycles. Drugs may be administered intravenously (into a vein), orally (by mouth), by injection into a muscle, topically (applied to the skin) or in other ways, depending on the drug and the type of cancer. Chemotherapy is often given in cycles of alternating treatment and rest periods. * Radiation Therapy is the treatment of cancer and other diseases with ionizing radiation. Ionizing radiation destroys cells, or the genetic material of cells, in the area being treated, thereby making it impossible for these cells to continue to grow. * Surgery involves removal of the tumor. Sometimes, surrounding tissue and lymph nodes are also removed. Surgery can be performed using conventional instruments or laser. * Hormone Therapy is the use of hormones to change the way hormones in the body help cancers to grow. * Biological Therapy (Immunotherapy) makes use of the body’s immune system, either directly or indirectly, to fight cancer and lessen the side effects that may be caused by some other cancer treatments. * Alternative and Complementary Therapy – includes herbal medicine, acupuncture and homeopathy.
Drug Treatment of Cancer
Drugs are used not only for treating cancer, but also for relieving symptoms of the cancer (e.g. pain), and side-effects, such as nausea, commonly seen with the various types of treatment.
Most anti-cancer drugs act by inhibiting DNA synthesis or some other process in the cell growth cycle. Because anti-cancer drugs generally affect rapidly dividing cells, other non-cancerous cells will also be affected. The way in which the other cells are affected determines the side-effects of the individual drugs. Other cells affected include blood cells, which fight infection, help the blood to clot, and carry oxygen to all parts of the body. When blood cells are affected, patients are more likely to get infections, may bruise or bleed easily, and may feel unusually weak and very tired. Rapidly dividing cells in hair roots, and cells that line the digestive tract, may also be affected.
As a result, side effects may include loss of hair, poor appetite, nausea and vomiting, diarrhoea, or mouth and lip sores. Many of these side effects can now be controlled, thanks to new or improved drugs. Side effects generally are short-term and gradually go away. Hair grows back, but it may be different in colour and texture.