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What is cancer?

The organs and tissues of the body are made up of tiny building blocks called cells. Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, the division and growth of cells is orderly and controlled but if this process gets out of control for some reason, the cells will continue to divide and develop into a lump which is called a tumour. Tumours can either be benign or malignant. Cancer is the name given to a malignant tumour.
In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, if they continue to grow at the original site, they may cause a problem by pressing on the surrounding organs.
It is important to realise that cancer is not a single disease with a single type of treatment. There are more than 200 different kinds of cancer, each with its own name and treatment.

What is a cancer cell?

And just as there are hundreds of types of cell, there are hundreds of types of cancer, few of which can be treated in the same way. Every cell's life is mapped out in advance by coded instructions, called genes, held in its nucleus. These tell it how to behave, when to reproduce by dividing - and when to die.
When the instructions relating to cell multiplication and dying are wrong, the cell may start dividing uncontrollably, and not die when it should. In addition, the cancer may not follow the usual instructions that keep cells spaced out properly.
Every time the cell divides, the "bad" instruction is reproduced, so the out-of-control multiplication carries on. As these cells can be multiplying more rapidly than healthy cells, the cancer cells can form a growing lump in the body called a tumour or a lesion. As this gets larger, it can even grow its own vessels to keep it supplied with blood. A benign, or non-cancerous tumour shares this uncontrolled growth, but will not generally invade neighbouring tissues and damage them.
Tumours which do this are "malignant", or "cancerous". The type of cell in which the cancer starts will generally determine the speed at which it grows, and its resistance to treatment, although there are many variations.
Cancers harm health in a number of ways. The very size of the tumour can interfere with nearby organs, or ducts which carry important chemicals, causing pain or other symptoms.
For example, a tumour on the pancreas can grow to block the bile duct, leading to the patient developing obstructive jaundice. And a brain tumour can push on important parts of the brain, causing blackouts, fits and other problems. Even benign tumours can cause these problems if located in the wrong place.
When a cancer invade nearby tissues, they can cause bleeding from damaged blood vessels, and stop the organ which they are invading from working properly.

What happens if it spreads?

As a tumour grows, cells can break off and start growing on adjacent tissues and organs. For example, if a bowel cancer has spread through the wall of the bowel itself, it can start growing on the bladder. Cells can also enter the bloodstream and travel to distant organs, such as the lungs or brain. The technical term for this is "metastasis".
When new tumours form on distant organs, they behave like the original tumour - so a bowel cancer cell growing in the lung will not be lung cancer. Once other organs are involved, then any symptoms of the cancer can get worse. However, it may be some time before a growing cancer in certain parts of the body produces symptoms that the patient can notice. Once a cancer has started to spread beyond its original site, then the chances of a cure often begin to fall, as it becomes more difficult to treat.

How is it treated?

There are three principal ways of treating cancer:

The first is surgery, normally an operation to remove the cancerous growth, and, depending on its type, nearby tissues and organs.

A cancer patient may first undergo a minor operation called a biopsy to take a small sample of the cancer for analysis.
The surgeon will try to remove as much of the cancer as possible, but sometimes extra treatment will be needed.
This could either take the form of radiotherapy or chemotherapy, or a combination of treatments.

Types of cancer

About 85% of cancers are carcinomas. They start in the epithelium, which is the covering (or lining) of organs and of the body (the skin).
These form in the connective tissues of the body such as muscle, bone and fatty tissue (6% of cancers).
These occur in the tissues where white blood cells (which fight infection in the body) are formed, i.e. the bone marrow, and lymphatic system (5%).
Others forms of cancer
Brain tumours and other rare forms of cancer make up the other 4% of cancers.

Who gets cancer?

1 in 3 people will develop cancer during their lifetime, but cancer is not common in children or young people - it mainly occurs in the later years of life. Cancers can occur at any age, but the risk of developing cancer increases with age. Over 70% of all newly diagnosed cancers occur in people aged 60 years or more.
Some cancers are very common and others are very rare. The most recent statistics for the UK show that for men the most common cancer is lung cancer (19%), followed by prostate cancer (17%), large bowel cancer (14%) and bladder cancer (7%). For women the figures are breast cancer (29%), large bowel cancer (12%), lung cancer (11%) and cancer of the ovary (5%).
Many people with cancer can be cured. Even if a cancer cannot be cured, it can often be controlled with treatment for months or years. Cancerbackup has information on all the main types of cancer, and on some of the rarer cancers.

Why do cancers come back?

A cancerous (malignant) tumour consists of cancer cells which have the ability to spread beyond the original site. If left untreated they may invade and destroy surrounding tissues. Sometimes cells break away from the original (primary) cancer and spread to other organs in the body by travelling in the bloodstream or lymphatic system. When these cells reach a new area of the body they may go on dividing and form a new tumour, often referred to as a "secondary" or a "metastasis".

Cancer Web Link
American Cancer Society - Information and Resources for Breast ...
Dedicated to helping persons who face cancer. Supports research, patient services, early detection, treatment and education.
Comprehensive Cancer Information - National Cancer Institute
Official site for the National Institute of Health's principal agency for cancer research.
Canadian Cancer Society - Société canadienne du cancer
Community-based organization aimed at the eradication of cancer and enhancement of the quality of life for people living with the condition.
Cancer Research UK: the UK's leading cancer charity
Funding world-class research and training to improve cancer treatment and prevention, and providing authoritative cancer information and advocacy.
Indonesian Cancer Foundation
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