What is cancer?

Cancer is a disease of the body’s cells. Each type of cell has a unique function: nerve cells carry crucial messages to and from the brain; blood cells carry oxygen and food to every body part and help fight infections; muscle cells contract and enable the body to move. For the most part each cell grows in a particular place and at a particular rate.

For various reasons – we don’t know all the answers – certain cells suddenly abandon their normal growth pattern and begin to reproduce uncontrollably – they become cancerous. As these cells multiply, they form a lump, or primary tumour. From this tumour, cancer cells often travel through the lymphatic system or the bloodstream to other parts of the body, and form tumour there as well. This spreading and clumping of cancerous cells is known as metastasis.[1]

In time the cancerous cells crowd out and replace the normal cells. The severity of the disease depends on the extent to which malignant cells spread and erode normal body functions.

WHERE DID THE NAME COME FROM ?

The term “cancer” comes from the Greek word for crab. The ancient Greek physician Hippocrates likened a spreading cancerous tumour to the shape of a crab’s claw. Although our understanding of the disease has advanced dramatically since then, the description is still apt.[2]

 

IS THERE ANYTHING I CAN DO TO AVOID GETTING CANCER ?

Yes there certainly is. There are some types of cancer that can be avoided by taking protective measures. Medical evidence indicates that certain environmental factors or agents do increase the risk that you will develop cancer. By avoiding such agents, which are labelled carcinogenic, or cancer-causing, you can reduce your chances of getting cancer. They include;

• Tobacco
• Vinyl chloride
• Asbestos
• Benzine
• X-rays
• Ultraviolet radiation from the sun
• Diet

Most doctors agree that it’s a good idea to familiarise yourself with these substances that are known carcinogens – and to avoid them to the best of your ability.

 

AGING and CANCER

Cancer is most common among older people, largely because their cells have had more time to accumulate genetic damage. Also the body’s defences against cancer, particularly the cells and proteins of the immune system, gradually become less efficient with age.

Since life expectancy increased significantly in the second half of the 20^th century, cancer has now become one of the most common causes of death, second only in the UK to coronary artery disease.

The lifetime risk of women developing cancer is one in nine.

Breast cancer is second to lung cancer as the leading cause of cancer-related deaths among British Women.[3]  Eighty percent of breast cancers occur in post-menopausal women. The average age of women diagnosed with breast cancer is 64 years. However one third of women diagnosed with breast cancer are younger than 50 years.[4] [see dMAC Health Digest  ‘Breast Cancer – Early Detection Saves Lives’ – Oct-2005]

CANCER TREATMENT

The three basic types of cancer treatment are surgery, radiotherapy and chemotherapy, or treatment with anti-cancer drugs. Two or more of these approaches may be used in combination to help a cancer patient. In addition there are new types of treatment still in the experimental stage. They include various ways of stimulating a person’s immune system to detect and destroy cancer sells. [see dMAC Health Digest ‘An Orange A Day Keeps Cancer at Bay’ Jun-2004]

Surgical treatment is the oldest and still the primary form of cancer treatment. Given the right conditions, it may be possible to remove completely a cancerous growth. Not all cancers can be attacked surgically e.g. cancers of the blood. Certain cancers that have spread throughout the system cannot be cut.

Various types of surgery can be used. Most are removed with a knife or scalpel but other forms of tissue removal are used. These include cryosurgery (freezing of cancerous tissue); diathermy or electro surgery (electric current is used to destroy tissue); chemosurgery which involves the application of tissue-destroying chemicals directly to a tumour; and laser beams to kill cancer sells. The first three types tend to be used on cancers of the skin, mouth and rectum. Laser surgery is often used to treat eye, brain and gynaecological cancers.

Radiotherapy is a form of energy that can damage any kind of living cell. If the radiation is aimed properly and is the right strength it can destroy cancer cells without seriously injuring or permanently damaging nearby normal cells. Radiation can be can often be controlled so that it will pass through healthy tissue and attack cancer cells that may be difficult or impossible to reach with surgery.

Types of radiation include the familiar X-rays, produced by an electrically powered machine; radioactive elements such as cobalt, iodine and radium.

Cobalt is used in a special machine that beams radiation into the body from the outside.

Radioactive iodine can be implanted in the form of wires or pellets to bombard cancer cells 24 hours a day. Radioactive iodine can also be injected directly into the blood. The iodine travels through the body but is concentrated in cells that have a special need for iodine, such as the thyroid gland. Thus radioactive iodine is an effective way to treat cancers of the thyroid.

Radium or more usually these days, radioactive calcium is often used in gynaelogical cancers.

Radiation itself can actually cause cancer. To minimise this danger a radiotherapist uses the least amount of radiation required to attack a tumour.

Using modern equipment such as the linear accelerator and taking special care to focus the radiation on cancerous tissue, should limit its impact on normal cells. Some doctors avoid using radiotherapy to treat cancer s involving organs especially sensitive to radiation, such as kidneys, lungs and liver. Other organs that must be protected from radiation are a woman’s ovaries and a man’s testes.

Chemotherapy is the use of powerful drugs to kill cancer cells at the microscopic level. Anticancer drugs may be given as primary therapy e.g. treatment of certain lymphomas (cancer of the lymph nodes – a small mass of tissue that cleans the colourless fluid containing white blood cells) and leukaemia’s (the white corpuscles multiply uncontrollably in the body tissue, usually the blood).

They may also be administered after surgery or radiotherapy in order to kill any remaining cancer sells. In all cases the goal is the same: to kill as many cancer cells as possible, even if the cells have not formed tumours.

Anticancer drugs are given by mouth or injection so that they pass through tissues all over the body and kill cancer cells wherever they are found. One exception to this is the brain; it has a protective barrier that few drugs can penetrate.

Chemotherapy side effects are very broad. They include

• Nausea
• Vomiting
• Skin rash
• Hair loss
• Mouth ulcers
• Low blood counts
• Diarrhoea
• Fluid retention
• High blood pressure
• Loss of sex drive
• Hot flushes
• Numbness in limbs

A more serious side effect of certain anti-cancer drugs is the suppression of the patient’s immune system. This occurs when the drug kills not only cancer cells, but also normal cells of the bone marrow where many of the white blood cells that fight infection are made. If damage is great the patient may not be able to resist the attacks of bacteria, viruses or fungi – and such infections can kill.

In many cases patients have to put up with the discomforts and risks of chemotherapy in the expectation that the treatment will slow down, stop or reverse the growth of cancer.

CAN WE EXPECT A CANCER CURE IN THE NEAR FUTURE ?

Because cancer is many diseases with some common traits, many scientists believe that no single treatment will ever be found to cure all cancers.

For many reasons – most of which are not well defined - our immune system seems not to recognise cancer as an invader, and so does not attack or attacks weakly and ineffectively. Some scientists believe that many cancers might be destroyed by boosting or somehow harnessing the immune system – our body’s own special defence system against disease.

Nanoshells – precision-guided tumour killers. - Experiments being carried out at Massachusetts Institute of Technology and Harvard University are infusing hollow spheres of carbon polymer (nanoshells), each 1,000 times as small as a pinpoint, with miniscule doses of chemotherapy drugs. To ensure the nanoshells strike only the cancer cells, researchers stud them with a string of molecules called aptamers, that bind exclusively to proteins that sprout from cancerous tissue. Once the nanoshells arrive at their pre-ordained location, they deposit their anti-cancer cargo inside the cancer cells, killing them off – without harming the healthy cells. When will nanoshells be available? – Possibly not before 2014 – three more years of animal testing, plus five years testing on humans[5].