WHAT IS CANCER?
Our bodies are made up of millions of building blocks called cells. Cancer occurs when one or more of the cells breaks free from the normal restraints it is under and starts to multiply in an abnormal, uncontrolled way. This can happen to more or less any type of cell (bone, skin, blood etc.) so there are as many types of cancers as there are different cells in the body- about 200! Unfortunately for us, all these diseases have different causes different symptoms and often respond differently to treatment.
In General, one in four of us will suffer from some form of cancer at some time in our lives. So it's likely that every family will come into contact with the disease in some way. Different cancers affect people at different ages, but the risk of getting the disease rises rapidly as we get older.
What Causes Cancer?
Each cell in our body has a control center, or nucleus, which gives the cell instructions as to how it should behave. The instructions tell the cell what type it should be (e.g. a bone, skin or blood cell, and so on), where it should live in the body and when it should make more copies of itself. The nucleus contains a blueprint for all these instructions, written in special code. Each coded instruction is called a gene.
In cancer, cells go wrong as a result of faults in their genes, which means that there are mistakes in the cell's instructions. Genetic faults can either be inherited from our parents, or more often they are the result of damage by cancer-causing agents such as tobacco, viruses, sunlight or dietary factors that we encounter from day to day. It takes more than one fault to turn a cell into a cancer cell, but as we go through our lives, we tend to accumulate these genetic mistakes. This is one reason why we are more likely to develop cancer when we are older. Cancer-causing agents that damage genes are known as carcinogens. Below are some of the main known and suspected causes of cancers.
Tobacco smoking causes nine out of ten cases of lung cancer. Many other cancers have also been linked to tobacco, including cancers of the mouth, throat, food pipe, bladder, cervix, pancreas, stomach, kidney and leukemia. Overall, one third
of all cancer deaths in the UK are caused by tobacco. There are 3,000 chemical compounds in tobacco smoke. The most important are nicotine (which is addictive), tar (which contains numerous carcinogens) and carbon monoxide. Several hundred people die every year from lung cancer caused by passive smoking- breathing other people's tobacco smoke. For more information on tobacco and cancer, please go to Tobacco
It is now believed that up to a third of all cancers in westernized countries may be linked to diet. It seems that different types of food can either have a harmful or a protective effect and there is still much to be learnt about which foods should be avoided, or eaten in moderation, and which should be eaten regularly. It has, however, been clearly established that fruit and vegetables are protective, probably due to numerous constituents. Diet seems to play a particularly important role in bowel cancer. Research shows that a diet rich in fiber and starchy foods and low in fat, with moderate alcohol intake, may help reduce the risk of bowel cancer. Currently, most people in the UK are not eating enough fibers.
Most people find that being in the sun makes them feel better and happier. We get vitamin D from sunlight too, although it is possible to get all the vitamin D you need from your diet. But sunlight contains different types of radiation, some of which can cause sunburn or more serious damage. Skin cancers are linked with the amount of radiation from the sun that reaches the skin. Most skin cancers, however, can be prevented if adequate precautions are taken against the sun.
Radiation is used to treat cancer because the radiation damages the cancer cells enough for them to die. However, radiation can also cause cancer. The first evidence of this was the high incidence of cancer of the head and bone found in a certain group of young women, earlier this century. The women in this group used to paint luminous figures on the dials of watches using radioactive paint. Many of them developed cancer as a result of putting their paint brushes (and the radio-activity) into their mouths, to shape them into points.
There are some viruses that appear to play a key role in causing certain cancers. These viruses are often found in many people in the normal healthy population, not just in the few that develop cancer. When a virus infects someone, it finds its way into a particular cell. For instance, hepatitis viruses infect a person's liver cells. Some viruses deliberately interfere with the cell's genetic instructions to service their own needs. This can 'accidentally' lead to cancer. For example, the Epstein Barr virus has been linked with some cancers of the lymph glands in the western world, and with nose and throat cancer in South East Asia, while the genital wart virus has been linked with cancer of the cervix.
Various chemicals used in industry have been shown to cause certain cancers. Examples are asbestos dust, which can cause a type of lung cancer, and vinyl chloride (the raw material for PVC), which can cause liver cancer. Several commonly used organic solvents are classified as carcinogens. These materials can induce cancers through prolonged skin exposure or inhalation. Employers, employees and trades unions should be aware of any carcinogens involved in their industry and make sure that safety precautions are always followed.
How Do Cancers Develop?
Healthy cells divide and increase in number as we grow or as the body repairs itself. When enough cells have been produced for a particular purpose this dividing mechanism switches off naturally. In cancer cells, the dividing process goes out of control because the genetic instructions are faulty. As a result, cancer cells divide when it is not necessary and then continue to increase in number, forming a mass of abnormal cells. These cells don't work properly as part of the organ or tissue where they began. They become interested only in reproducing themselves, and are unable to know when to stop. Normal cells often have a limited life span. They are pre-programmed to die when they are too old or if they start malfunctioning. Cancer cells override this pre-programming and become immortal. As the cells multiply, the mass of cells (or tumor) takes up more and more room. It may invade nearby parts of the body and prevent them from working properly. Not all tumors are cancers. If the tumor is enclosed and does not spread it is called a benign tumor, which is usually harmless. If the tumor spreads into the normal tissue surrounding it or further, it is called a malignant tumor or cancer.
How Do Cancers Spread?
Cancers are not infectious and do not spread from person to person. However, once they advance beyond a certain point, they become able to spread within a person. A tumor that has the potential to spread is said to be malignant because it has more serious implications for the patient. Cancers spread by invading the surrounding tissue until they reach a blood or lymph vessel. Small groups of cells may then break off from the original tumor (known as the primary tumor). These are then carried via the bloodstream (or lymph vessels) to other parts of the body, where they may settle and grow. This process is called metastasizing (or metastatic-spread). The new cancers that develop are known as a secondary cancers (or just secondaries).
Is Cancer Hereditary?
Faulty genes that run in some families may cause a small number of cancers (5 to 10 per cent). Since one in three of us develops cancer at some time in our lives, having one or two relatives with cancer is unlikely to mean that you are more at risk. The main pointers to a cancer that may be running in the family are:
Several cancers of the same type in the family cancers occurring at young ages (e.g. before the age of 50 years)
Several cases of cancer on the same side of the family
But remember that even if one of your parents carries a faulty gene, it does not necessarily mean that you will inherit it.
How Do You Know If You Have Cancer?
If you are worried that you have cancer, you should see your GP straightaway. Below is a list of health problems drawn up by experts, which may indicate cancer. It should be emphasized however, that many of the symptoms that are caused by a cancer are often also caused by a variety of other medical problems that are far less serious than cancer.
Are There Any Ways of Detecting Cancer Early?
With some cancers, it is possible to detect the cancer while it is still at an early stage, often before the patient has noticed any symptoms. Where possible, screening programs are set up for people who are more at risk, for instance because of their age or their family health background. You can find out more about screening for breast, cervical, bowel, and ovarian or prostate cancer in our section on Screening.
Can I Prevent Myself from Getting Cancer?
It is unlikely that we will ever be able to prevent all cancers completely. However, scientific research funded by the Cancer Research Campaign and others is gradually giving us a clearer picture of how we can reduce our risk of cancer. You can find out more about reducing the risk of cancer in our section on reducing risk.
The three main types of treatment for cancer are surgery, chemotherapy and radiotherapy. If you have been diagnosed with cancer, the treatment you will be given depends on the type of cancer that you have and whether it has spread. Sometimes people are given a combination of two or more types of treatment.
This is an operation to remove the cancer. Surgery is often combined with other types of treatment to make sure that all the cancer cells are killed.
This means using specialized machines to direct beams of radiation at the area of the body where the cancer cells are. The radiation kills or inactivates the cancer cells so they stop dividing and the tumor stops growing. Sometimes radiotherapy is used to shrink the tumor so that it is easier to remove by surgery.
This means treating the cancer cells with drugs that are designed to kill them. The drugs are carried around in the bloodstream and so can reach different areas in the body at the same time. For instance, it is an effective treatment for leukemia, cancer of the blood cells, where the disease is present throughout the body.
Most treatments for cancer have some side effects associated with them. You should discuss this with your doctor, as the side effects vary considerably depending on the type of cancer and the type of treatment. Cancer Research Campaign researchers and others are currently working on ways to prevent or reduce the side effects of cancer treatments.
What Is A Clinical Trial?
Researchers are constantly looking for new and improved ways of treating cancer. When we believe there might be an improvement to the standard treatment, a detailed and careful comparison must be made. This is usually done by means of a study with patients, known as a clinical trial. In order to remove any bias that may come from the doctor or the patient, the patients are entered into the trial by randomization. This means that whether you get the standard treatment or the newer treatment is decided randomly by a computer in the management office of the trial. If a trial shows that one treatment really is dramatically better than the other is, the trial will be stopped early and everyone will receive the better treatment. This is not likely to happen unless the results are truly impressive. Nevertheless, it is important for patients to realize that they are not being denied access to any miracle treatment that may be found. It is a good idea to ask your doctor about any clinical trials that may be going on, as there is evidence that all groups of patients do better when they participate in clinical trials.
In continuation to this introductory article additional articles will be brought into this site shortly detailing specific types of cancers in human subjects and the best available chemotherapy up to date.