Why there are different kind of cancers?

cancer cells

Of all the diseases that may afflict us, none is more feared than cancer. In the past two decades medical science has made enormous progress in unravelling the mysteries of cancer and in treating it. And yet, even though a patients chances of surviving are greater today that they have ever been, the death toll from cancer continues to rise. It is much higher than it was forty years ago.

That, strangle, is a sign of our improving health. Life expectancy today is higher. Many diseases that in the past were often fatal – cholera, malaria, poliomyelitis, typhoid, pneumonia – no longer hold such dangers in the world’s developed countries. Because more of us are living longer, we expose ourselves in our sixties and seventies to attack from heart disease an strokes, today’s major killer, and to any of the wide variety of cancers.

Most people fear cancer more than they do a heart attack or a stroke, because they mistakenly believe that death is inevitable. Certainly, the death rate for cancer is till high, accounting for at least 20 percent of death is in the United States, in Britain and many parts of Europe. But about 40 percent of the million Americans and the 220,000 Britons who are diagnosed each year as having cancer get early treatment and live for many years after it; many of them are fully cured.

One reason why cancer is so feared is because it takes so many forms. It is not one disease but more than 100, all having common factor. Most people know that there are two forms of tumour, or abnormal growth of tissue. One is benign and grows slowly. Its main distinction is that, once formed, it stays where it is. In all cancers, malignant tumours sometimes grow rapidly, and they spread affecting not only healthy tissues nearby but often invading vital parts of the body, such as the lungs, breasts and stomach. Sometimes, they do this by what doctors call metastasis. Cancer cells break away from the original growth, and travel in the bold stream. Or they may invade the lymphatic system which,  among a range of jobs, defends us against bacteria. Once into either of these two conveyors the errant cells may attack parts of the body far from the original site.

Why this happens is not fully understood, but it may be because of predisposition, an inherited susceptibility, to the disease. That doesn’t mean that cancer itself is inherited. Because one of your relatives had cancer is no reason for believing that you will inevitably get it.

All of us have some 50,000 or more separate genes that determine every facet of our make-up. It seems that some of these – perhaps no more than 100 – begin to malfunction. These genes, known as oncogenes, control cell growth and multiplication. Suddenly, some cells grow abnormally and multiply uncontrollably. Eventually there’s no room for normal cells alongside these mavericks. The normal cells get crowded out and replaced. If that happens swiftly, the attack is severe. Usually, it occurs more slowly and gives early warning signs.

From our increasing knowledge of the disease we know that a trigger of some kind can in some circumstances propel the wayward cells into action. These the wayward cells into action. These triggers, known as carcinogens, do not necessarily cause the disease, and that is one of its puzzles. For example, tobacco smoke is a recognized carcinogen, but everybody knows a heavy smoker who survives to old age without getting lung cancer. On the other hand, for every defiant, elderly smoker there are dozens who have had their lives cut short. Doctors say that genetic make-up, which is inherited, explains why a carcinogen sets off cancer in some people but not in others.

As research continues, medical scientists identify more cancer triggers. We know that radioactive chemicals are high on the list, as the grim evidence from Chernobyl continues to tell us. So are other forms of radiation, such as from X-rays and the Sun. The list includes chemicals found in pesticides, industrial waste, car exhausts, building materials such as asbestos and fiberglass wool, and processed foods.

Sexual behaviour affects a woman’s chances of getting a cervical cancer: the more partners, the higher the risk. And having children while relatively young seems to reduce the changes of breast cancer. Chronic irritation may be another trigger. For example, ill-fitting dentures are blamed for some mouth and lip cancers.

Because, as each year goes by, we can point to an increasing list of cancer triggers, our defences against this range of diseases constantly grow. We know that smoking is a major cause (not only of cancer but of cardiovascular diseases also). About 30 percent of all cancer victims are smokers.

If the smoker is also a heavy drinker, the risk rises not only for lung cancer but other cancers. Tests show that such a person of forty-four times more likely to get cancer of the oesophagus than somebody who drinks the same amount but smokes ten or fewer cigarettes a day. Smoking carries lung-cancer dangers not only for the smoker. Studies show that nonsmoker are forced every day to breathe a dangerous cocktail of chemicals in areas polluted by tobacco smoke. Around the world it is believed that thousands of nonsmokers die from cancer caused by passive smoking in public places and encouraging smokers to stop are to clear-cut ways to reduce cancer.

Sound diet is another. Studies suggest that food – too much of some things and too little of others – is a contributing factor in 35 percent of all fatal cancers. Because the range of foods and food additives is so waste, it is almost impossible to pinpoint specific cuprits. However, fatty meats, oils and dairy products appear to increase the risk of cancer in the breast, the stomach and colon. The intake of all preserved foods – smoked, pickled and salted – also should be limited.

More positively, some foods seem to offer protection. Fiber-rich foods, such as whole-grain cereals, fruits and vegetables , insure against bowel cancer. People who get plenty of vitamins A and C, which are abundant on spinach, capsicums, Brussels sprouts and broccoli, appear to get fewer cancers of the respiratory and digestive systems.

We know, too, that the incidence of skin cancers rises with increasing exposure to the Sun. About 20 percent of residents in Queensland, Australia, will suffer some form of skin cancer by the age of seventy-five, the world’s highest incidence. Residents in the southeastern and southwestern United States run them a close second. Sensible precautions – wearing a hat, using effective sunscreens, less sunbathing – will undoubtedly cut the toll.

Prevention is clearly the most sensible course. But cancers range so widely that many cannot be avoided. The second smart strategy is early detection. Screening tests for cervical, breast and intestinal cancers, for example, have now significantly reduced the death rate from these diseases.

Cancer gives many warning signs. Sudden loss of weight, sores or ulcers that fail to heal within normal time, recurrent hoarseness, persistent pain of any kind, a lump or swelling, any discharge of bold … all these are signals that should send a victim to a doctor.

Today, almost half of all cancers can be cured completely. The range of treatments grows constantly wider and more effective. But improved therapy gets its best chance  when coupled with early detection. In using that defence and in taking intelligent preventive measures, all of us are our own best doctors.

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