Can cancer be inherited?
Cancer isn't passed on in the same way as, say, blue eyes or blonde hair. (One such cancer is a rare eye cancer called retinoblastoma.) However, certain cancers, such as breast, bowel and ovarian cancers, do cluster in some families, and may be caused by a single gene. Others may have inherited pre-cancerous conditions, such as polyposis coli - small growths on the large bowel which can turn into bowel cancer.
My husband smokes. Does this mean I have a higher risk of lung cancer?
Passive smokers stand a 10 to 30 per cent higher risk of contracting lung cancer - a good reason to encourage your husband to give up cigarettes.
Is there a link between stress and cancer?
There's no hard evidence that stress boosts the risk of cancer, though it can affect the immune system. Trials are now being done to see if relaxation can improve the body's defences against cancer.
Of all the medical conditions, cancer is probably the most dreaded and feared. But early diagnosis and ever-improving modern treatments can often lead to a complete cure.
One in three of us in the UK will suffer from cancer at some time in our life, and one in five of us will die from it. The most common cancers are lung, breast, bowel, ovary, kidney and melanoma - the most dangerous form of skin cancer.
The good news is that almost a third of the people who develop cancer will be cured. And many more will live for several years with the disease, without any problems directly linked to it.
HOW CANCER DEVELOPS
Our bodies are made up of a variety of different tissues. Each is made up of millions of cells, all arranged in an orderly manner. The appearance and shape of cells from different organs and tissues vary. For example, liver cells are completely different to skin cells.
Throughout our lives, cells are constantly lost and replaced by a process of division. Normally this process is under strict control, so that exactly the right number are produced to replace those that are lost. If an injury occurs, the rate of cell production speeds up until it has healed, then slows down again.
OUT OF CONTROL
Malignant cancer cells divide and grow uncontrollably and will continue to do so indefinitely unless some form of treatment is given. Eventually, they become so numerous that they are visible as a tumour or growth.
Cancer cells develop from the body's own normal cells in a series of stages that takes place over many years. The first step is a damaged gene in an individual cell.
The faulty gene may be inherited or it may be triggered by factors such as smoking, over-exposure to the sun, or certain types of bacterial or viral infection.
But, once it has developed, it switches off another gene which tells the cell when to stop dividing.
Abnormal cells are produced all the time, but are destroyed by the body's defence system. When cancer occurs, for some unknown reason, the system breaks down and an abnormal cell survives.
LACK OF RESPONSE
The cell becomes progressively more abnormal and responds less and less to the body's normal control mechanisms. Eventually, there are enough cancerous cells to form a tumour. Cells from the edge of the tumour then invade and damage the surrounding tissues.
Though cancer usually develops unseen, the cells can often be recognized before they become cancerous. For example, a cervical smear test is designed to pick up abnormal cells in the cervix at a pre-cancerous stage when they can be easily treated.
To most of us, the word 'tumour' automatically signifies cancer. But, in fact, most tumours are found to be benign, or harmless. Unlike malignant tumour cells, benign tumours go on dividing, and may even push aside normal tissue, but they do not invade it. They are also unlikely to spread.
It's the ability of cancer cells to spread, or metastasize, that makes the disease so serious. Cancers which metastasize early on are called aggressive tumours, while others don't start to spread until a later stage. Tumours are often graded depending on how aggressive they are.
The cells spread via the blood and the lymph - fluid produced by the lymphatic system, which is part of the immune system At first, they pass into blood vessels in the primary, or original, tumour. They may also pass into the lymphatic system of surrounding tissues, from where they drain back into the bloodstream. As the blood travels round the body, some of the cells become stuck at the end of fine blood vessels called capillaries in various organs elsewhere.
In a second stage of metastatis, the cancer cells pass through the walls of the blood capillaries and enter a nearby organ, such as the lungs, liver, bone or brain. This organ is often far away from the original tumour. Most of these cells die but some may survive to form secondary tumours, which may also begin to metastasize.
A change in bowel or bladder habits.
A persistent sore throat, cough or hoarseness.
Unexplained weight loss.
Obvious change in size or bleeding of a mole.
Unusual bleeding or discharge.
Thickening or lump in the breast, testicle or elsewhere.
WHAT CAUSES CANCER?
Cancer is not just one disease. There are hundreds of different types, but they all occur when cells multiply in an uncontrolled way. Cancer has many different causes. The biggest known risk factor is smoking, which causes over a third of cancers and is responsible for a similar number of cancer deaths.
THE AGE CONNECTION
However, cancer is mainly a disease of old age. Though the overall risk of death from cancer has actually gone up by six per cent over the past 30 years, this is largely because, thanks to modern medicine, better diet, sanitation and hygiene, we are living long enough to reach an age when we are at a high risk of cancer.
This risk varies and depends on certain factors such as age, inherited characteristics such as a fair skin, which increases the risk of skin cancer, and inherited faulty genes, which will increase the background risk of certain types of cancer.
In the race for a cancer cure, early diagnosis is vital - a small cancer tumour is usually easier to treat than a welldeveloped one.
The first step in the diagnostic process is for you to be alert to any suspicious symptoms, particularly bleeding, and report them to your doctor as soon as possible. Of course, these symptoms will probably turn out not to be cancer, but it's better to be safe than sorry.
For most of us, a diagnosis of cancer is devastating news, but it is no longer an inevitable death sentence. There has been a vast improvement in diagnosis and treatment in recent years. Far fewer children now die of cancer than they did 20 years ago; there has been a significant decrease in stomach and bowel cancer in adults, and lung cancer among men has also gone down.
At the same time, improved treatments have led to people with other sorts of cancer surviving longer. For example, the discovery of hormonal or cell-killing drugs, plus a new awareness of the best time to perform surgery, has led to more women living longer with breast cancer.
You should never ignore suspicious symptoms such as:
Bleeding from the anus, which can be a sign of bowel cancer.
Bleeding from the vagina, either between periods or after the menopause, can be a symptom of both cervical or uterine cancer, especially in older women.
Blood in the urine could be a clue to kidney or bowel cancer.
Blood in vomit should never be ignored, unless you have had a recent nosebleed, as it can be a sign of stomach cancer.
A persistent cough or hoarseness that isn't associated with a cold or chest infection and goes on for longer than two weeks can be a sign of cancer of the larynx or cancer of the lung.
Many forms of cancer can be treated by means of radiotherapy. Here, a woman cancer patient is being prepared for treatment. The white device behind the radiographer rotates around the patient's head, delivering penetrating rays which are beamed towards the tumour.
A change in bowel habits, for example going to the toilet more or less frequently than usual, having alternate constipation or diarrhoea, dark streaks in the stools or having black, tarry stools, are signs of bleeding in the intestine.
See the doctor, too, if you are losing weight without dieting - the loss could be around 22kg (l0lbs) over 10 weeks or less - especially if this is combined with abdominal pain or a change in bowel habits.
If the doctor suspects you may have cancer, he will refer you to your local hospital for tests and diagnosis. Initial tests may involve investigations such as X-rays and ultrasound, which can reveal the presence of a lump.
A part of the suspicious tissue will then be examined under the microscope. This can be done either by biopsy - snipping off a small piece of the tissue for examination - or by cytology, which is studying cells from body fluids such as sputum or cervical mucus for cancer cells.
The doctor will then perform a thorough clinical examination, taking particular care to check the lymph nodes adjacent to the tumour to see whether the cancer has spread. Simple blood tests are then run to check liver and bone function and a chest X-ray looks for evidence of spread to these sites.
If the doctor suspects cancer has spread elsewhere in the body, this area may also be scanned.
HOW SCANS WORK
The scanning technique used is usually isotope scanning, where a small amount of a radioactive substance is injected into the body and the blood carries it to the suspected organ or area of tissue. Here, it is scanned using a special instrument which detects radiation. Cancerous cells are clearly visible because they take up a different amount of radioactivity than healthy tissue. Once the doctor has detailed knowledge of the type of cancer, its stage of development and its likely progress, he can then plan a treatment regime with the patient.
The aim of cancer treatment is to kill or remove every cancer cell from the patient. There are several different forms of treatment, which may be used alone or may be combined, depending on the nature of the cancer.
REMOVING THE TUMOUR
Surgery is most often used to treat cancer of the skin, stomach, bowel, uterus, breast and testicle. It may also be used to cut out cancers in the face and neck, including the thyroid gland and larynx, or voice box, as well as cancers of the ovary and the prostate gland.
As it is vital to remove all the cancerous tissue, the surgeon will cut out the tumour together with some surrounding normal tissue. Since cancer usually spreads first to lymph glands in the area near the tumour, the surgeon may need to remove these too.
Where possible, the surgeon will also reconstruct the area in which the cancerous tissue has been surgically removed. For example, if you have had a mastectomy, or breast removal, there are various techniques for giving you a new breast These include using muscle from other parts of the body, such as the shoulder, and inserting a breast implant.
In many cases, surgery alone is all that is required. However, additional forms of treatment may be given before or after surgery to make it easier and more effective. Doctors call this way of giving treatment adjuvant therapy.
High energy rays are used to damage the genetic material of cancer cells so they are unable to divide. These might be X-rays, or beta or gamma rays from a radioactive source. The rays are beamed carefully at the area to be treated. Cancer cells are more sensitive to radiotherapy than normal cells, and so are killed at a greater rate.
Inevitably, radiotherapy also damages normal cells close to the tumour. But, thanks to the body's ability to repair itself, quite large doses of radiation can usually safely be given, provided the treatment is given slowly. Treatment only lasts a few minutes, is painless and is usually given daily on an out-patient basis for five to six weeks.
Radiotherapy treatment may also be given externally, using special X-ray machines which direct the rays to the body.
In some cases radioactive implants, such as special wires, are inserted into the cancer, allowing large doses of radioactivity to be delivered to the tumour itself with only a small amount directed to the surrounding normal tissue. In cancer of the thyroid gland, a radioactive drink of iodine is sometimes used to destroy cancerous cells painlessly.
Chemotherapy is usually given by injection, through an infusion, or drip, or occasionally as tablets and capsules.
Some people experience few side-effects from radiotherapy apart from tiredness. However, radiotherapy can make you feel unwell, particularly if you have been feeling ill beforehand as a result of the cancer.
Other side-effects may include nausea, vomiting, headaches, diarrhoea and, where radiation is aimed at the stomach or head, a sore mouth. Hair loss may also occur if the head is treated but hair usually regrows within six months.
Radiotherapy may also be used to relieve symptoms of cancer, particularly pain, in cases where a cure is not possible.
Chemotherapy involves treating cancer with cytotoxic, or cellpoisoning, drugs. These destroy cancer cells by combining with and damaging the genetic material of the cells so that they cannot divide. Unfortunately, these drugs poison all rapidly dividing cells, causing side-effects such as hair loss, nausea and a lowered blood count.
Damage to normal cells can be minimized by giving large doses of drugs all at once, then leaving a gap of a few weeks before the next treatment to allow normal cells to recover. Chemotherapy may be given intravenously, injected into a muscle, or by mouth.
Where there is a risk of relapse after surgery and/or radiotherapy, chemotherapy is given even when there is no sign of cancer present.
This treatment technique is known as adjuvant chemotherapy.
Some cancers are affected by hormonal levels in the body. Hormone therapy involves either blocking, reducing or increasing hormone levels to act on the cancer. The main types of cancer treated in this way include certain types of breast cancer as well as prostate, thyroid and uterine cancers. Leukaemia, lymphomas and cancers of the lymphatic system, such as Hodgkin's disease, can also be treated.
Biological therapies are a group of treatments which use natural substances made by the body's immune system, such as cytokines, in order to control cell growth, to increase the body's defences against cancer cells or to boost the production of antibodies to fight cancer cells.
Substances known as colonystimulating factors are also used to help the body recover from the effects of treatment. The therapies are given by injection. At present, most of them are still being tested in clinical trials.
More effective therapy
As scientists discover more about how cells work, they are developing better treatments. These include drugs attached to antibodies, designed to 'recognize' cancer cells; drugs that block growth factors - substances which encourage cells to grow; and drugs that prevent cancer cells from invading other tissues. Scientists are also beginning to understand how cancer cells turn on and switch off enzymes in the body, which should lead to more effective anti-cancer drugs. Doctors are also working on better ways of detecting cancer. For example, a blood test for a gene thought to lie behind clusters of cancers of the breast, cervix and bowel may be available within the next few years.
Though all types of cancer therapy create side-effects, with modern methods of management these need not be too troublesome. Common side-effects, such as nausea and vomiting, can be managed with anti-sickness drugs. Mouth ulcers can be prevented by the use of mouth washes and a pain-killing gel. Unfortunately, the embarrassment of hair loss is usually only avoided by wearing a wig, though the hair will grow back.
A HELPING HAND
Complementary therapies, such as homeopathy, herbalism, healing and acupuncture, are often used in conjunction with conventional medical treatments for cancer. And, today, some cancer units actually offer these treatments to patients. They can help you to relax and to cope with the strain of treatment. At the same time, they may give you back a feeling of being in control of your own body.
Screening is performed for common cancers which affect a large number of people. It may also be worthwhile if you know you have a high risk of contracting cancer, for example if your work exposes you to substances known to cause cancer, or if you come from a family with a history of cancers. Screening is a means of detecting early cancers even before there are any signs and symptoms. This means that the cancer can be treated without delay, enhancing the patient's chances of survival. At present, the only national screening programmes are the cervical smear test and mammography both for women. A national bowel screening programme for both men and women may be set up, which tests for hidden blood in the stools. In the meantime, people at higher risk of the disease, for example because it runs in their families, can ask to be screened by their doctor or at one of the family cancer clinics for ovarian, testicular or prostate cancer.
All cancer cells share certain characteristics:
They are long-lived and not subject to the normal bodily influences that control cell growth. They can invade, or grow into, normal tissue.
They can migrate to distant tissue and form new tumours.
They may divide faster than normal.
The body tolerates the presence of cancer without rejecting it as a foreign invader.
Laser treatment is used to activate a cancer-killing drug.
Cancerous cells from a prostate tumour have spread to form metastases, or secondary cancers, in the vertebrae. The orange shadows on a chest X-ray reveal cancer in both lungs.
Radiotherapy is a mainstay of cancer treatment. Accurate planning using aids such as scans is vital in order to cause minimal damage to the surrounding tissue.
A scan reveals cancerous cells which have formed a large tumour in the brain.
A natural killer cell attacks a cancer cell.
Derived from the Pacific yew tree, Taxol is proving effective against breast and ovarian cancers.
A doctor plans radiotherapy treatment with the aid of a computer. Treatment can
sometimes cause unpleasant side effects, such as nausea, vomiting and hair loss.
Taken from THE HEALTH FILE A Complete Medical Encyclopedia, A MARSHALL CAVENDISH REFERENCE COLLECTION by DR JOHN CORMACK, WEEKLY Australia, New Zealand, Malaysia Singapore Malta RSA Other Countries Namibia.
DR JOHN CORMACK, BDS MB BS MRCS LRCP, is the medical consultant to The Health File. The senior partner in an Essex based practice, he is also a member of the General Medical Council and has written for numerous magazines and newspapers as well as for the medical press. He is a regular broadcaster on television and radio and has scripted a number of award-winning educational videos.
Note: Where gender is unspecified, individuals are referred to as 'he', This usage is for convenience only and not intended to imply that all doctors and patients are male. Medicheck charts are only a rough guide to diagnosis, Always seek medical advice if you have worrying symptoms.
Copyright Marshall Cavendish 1995, Printed in Great Britain, Published by Marshall Cavendish Partworks Ltd, 119 Wardour Street, London WIV 3TD
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