Cancer is the abnormal growth, reproduction and
spread of cells derived from normal tissues in the body. There are about 200
different kinds of cancers.
Cells normally grow, reproduce and die in response
to signals inside and outside the body in an orderly way. Cells that divide
when new cells are not needed form too much tissue. This mass of extra tissue
can be benign (non-cancerous) or malignant (cancerous). Malignant tissues can
invade and damage other tissues and organs. Cancer cells can then break away
from the tumour and enter the bloodstream or lymphatic system, spreading the
cancer to other parts of the body.
A normal cell can become a cancer cell for no apparent
reason or because of repeated or heavy exposure to a carcinogenic, or cancer-causing,
substance such as tobacco or alcohol.
Apart from some cancers which are particularly
common in childhood, most adult cancers become more common as we get older.
It is believed that the risk of losing control over normal cell division increases
with increasing age.
The mutated cell divides into two new mutated cells
that divide into four mutated cells. This process continues until the mutated
cells form a mass called a tumour.
A tumour can be benign or malignant.
A benign (non-cancerous) tumour is self-contained
and the mutated cells will not invade surrounding tissue or travel through the
bloodstream to other sites. A self-contained tumour, such as a wart, is benign
and is generally not life-threatening and usually can be surgically removed.
A malignant (cancerous) tumour is where tumour
cells grow and divide, damage surrounding normal cells, and invade other body
sites. The greatest danger in a malignant tumour is its ability to spread throughout
the body a process called metastasis.
Metastasis is where the tumour cells grow, divide
and eventually enter the bloodstream, and travel to other body sites, implanting
themselves in healthy tissue and growing into new malignant tumours.
Gradually, with the progression of the cancer,
healthy cells die and the patient's health and functions deteriorate, often
resulting in death.
Most malignant cancers fall into one of three main
A carcinoma is a cancer that arises in the skin,
the colon (large bowel), the rectum, the bronchial tubes, the ducts of the pancreas
or gall-bladder, or the milk ducts of the breast. A carcinoma can be found on
any lining surface in the body.
A sarcoma is a cancer that arises from the substance
of solid tissues such as muscle, bone, lymph glands, blood vessels and fibrous
and other connective tissues. Bone cancer is an example of a sarcoma.
Leukaemia and lymphoma
Leukaemias are also classed as malignant (cancerous)
growths. Leukaemia is a cancer that originates from blood-forming cells, while
a lymphoma originates from cells within the immune system.
are the symptoms of cancer?
Because cancer includes many different conditions
that may affect many different organs or systems within the body, the range
of symptoms that can be produced by cancers is vast. The symptoms depend on
the location of the tumour, they tissue it originates from and the rate of growth.
Symptoms may be caused by the tumour itself or the effect of the tumour on surrounding
tissues, for example obstruction or bleeding into the bowel, lung or urinary
tract. Unexplained weight loss is a feature of many cancers.
There are some important warning signals that warrant
investigation. If you develop any of the following symptoms, you should report
them to your doctor:
- Rapid weight loss without apparent cause.
- A scab, sore or ulcer that fails to heal within
- A skin blemish or mole that changes in some
way either gets bigger, bleeds or becomes itchy.
- Severe recurrent headaches.
- Difficulty in swallowing.
- Persistent hoarseness.
- Coughing up blood-stained sputum (phlegm).
- Persistent abdominal pain.
- Change in size or shape of the testicles.
- Blood in the urine, with no pain on urination.
- Change in bowel habits.
- Lump or change in the breast shape.
- Bleeding or discharge from the nipple.
- Irregular vaginal bleeding or spotting between
periods or after menopause.
Remember that there may be other causes for these
symptoms. But if they are caused by cancer, the sooner you seek medical advice
the better as early detection increases the chances of cure.
is the outlook?
Almost half of all cancers can be completely cured
and the survival rates for the various cancers continue to improve. Cure and
survival rates and the chances of recurrences do differ considerably, however,
depending on the type of cancer and the stage
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