Cancers are a large family of diseases that involve abnormal cell growth with the potential to invade or spread to other parts of the body. There are more than 200 types of cancer. They form a subset of tumour. It is a group of cells that have undergone unregulated growth and will often form a mass or lump. All tumour cells show the six indications of cancer. These characteristics are required to produce a malignant tumour. They include: • Cell growth and division absent the proper signals • Continuous growth and division even given contrary signals • Avoidance of programmed cell death • Limitless number of cell divisions • Promoting blood vessel construction • Invasion of tissue and formation of metastases All cancers begin in cells. Our bodies are made of more than a hundred million cells (100 000 000 000 000). Cancer starts with changes in one cell or a small group of cells. Cells give signal to each other to stay together, this is because cells produce signals to control how much and how often the cells divide. If any of these signals are faulty or missing, cells may start to grow and multiply too much and form a limp called tumour. For a cancer to start, certain changes take place within the genes of a cell or a group of cells. Some genes get damaged every day and cells are very good at repairing them. But over time, the damage may build up. And once cells start growing too fast, they are not able to repair the damaged genes. When cancer begins, it produces no symptoms. Signs and symptoms appear as the mass grows or ulcerates. The findings that result depend on the cancer's type and location. Few symptoms are specific. Local symptoms may occur due to the mass of the tumour or its ulceration. For example, mass effects from lung cancer can block the bronchus resulting in cough or pneumonia; oesophageal cancer can cause narrowing of the oesophagus, making it difficult or painful to swallow. General symptoms occur due to effects that are not related to direct or metastatic spread. These may include: unintentional weight loss, fever, excessive fatigue and changes to the skin. Hodgkin disease, leukaemia's and cancers of the liver or can cause a persistent fever Cancer can spread from its original site by local spread, lymphatic spread to regional lymph nodes or by hematogenous spread via the blood to distant sites, known as metastasis. When cancer spreads by a hematogenous route, it usually spreads all over the body. Most of cancers, are due to genetic mutations from environmental factors. A few are due to inherited genetics. It is not generally possible to prove what caused a particular cancer because the various causes do not have specific fingerprints. For example, if a person who uses tobacco heavily develops lung cancer, then it was probably caused by the tobacco use, but since everyone has a small chance of developing lung cancer because of air pollution or radiation, the cancer may have developed for one of those reasons Exposure to substances have been linked to specific types of cancer. Tobacco is responsible for about one in five cancer deaths worldwide. Diet is very important factor. In our lifetime more than half of the effect from diet is due to eating too much, rather than from eating too few vegetables or other healthful foods. Some specific foods are linked to specific cancers. A high-salt diet is linked to gastric cancer, a frequent food contaminant, causes liver cancer. Betel nut chewing can cause oral cancer. Viruses are the usual infectious agents that cause cancer, but cancer bacteria and parasites may also play a role. Human papilloma virus can cause cervical cancer. Some of invasive cancers are related to radiation exposure, including both ionizing and no-ionizing radiation. Medical use of ionizing radiation is a small but growing source of radiation-induced cancers. Ionizing radiation may be used to treat other cancers, but this may, in some cases, induce a second form of cancer. Some hormones play a role in the development of cancer. These are important agents in sex-related cancers. Most cancers are initially recognized either because of the appearance of signs or symptoms or through screening. Neither of these leads to a definitive diagnosis, which requires the examination of a tissue sample by a pathologist. People with suspected cancer are investigated with medical tests. These commonly include blood tests, X-rays, CT scan, MRI and endoscopy. The tissue diagnosis from the biopsy indicates the type of cell that is proliferating, its histological grade, genetic abnormalities and other features. Together, this information is useful to evaluate the prognosis and to choose the best treatment. Many treatment options for cancer exist. The primary ones include surgery, chemotherapy, radiation therapy, hormonal therapy, targeted therapy and palliative care. Which treatments are used depends on the type, location and grade of the cancer as well as the patient's health and preferences. To spread, the cancer cell must first become detached from the primary cancer. It must then move through the wall of a blood vessel to get into the bloodstream. When it is in the bloodstream, it is swept along by the circulating blood until it gets stuck somewhere, usually in a very small blood vessel called a capillary. Then it must move back through the wall of the capillary and into the tissue of the organ close by. There it must start to multiply to grow a new tumour. This is a complicated journey. Most cancer cells do not survive it. Probably, out of many thousands of cancer cells that reach the blood circulation only one will survive to form a secondary cancer or metastasis. The way a cancer spreads through the lymphatic system is very like the way it spreads through the bloodstream. The cancer cell must become detached from the primary tumour. Then it travels in the circulating lymph fluid until it gets stuck in the small channels inside a lymph node. There it begins to grow into a secondary cancer. The lymphatic system is a system of thin tubes that runs throughout the body. These tubes are called lymph vessels or lymphatic vessels. The immune system is important to cancer patients in many ways because: • The cancer can weaken the immune system; • Cancer treatment can weaken the immune system; • The immune system may help to fight your cancer. Cancer can weaken the immune system by spreading into the bone marrow where the cells that help fight infection are made. This happens most often in leukaemia or lymphoma. But it can happen with other cancers too. Chemotherapy and radiotherapy can weaken immunity by causing a drop in the number of white blood cells made in the bone marrow. There are two main parts of the immune system: • The in-built protection we have from birth; • The immune protection we develop from being exposed to certain diseases. If you are having cancer treatment, it is important for you to know that • Infections can become serious more quickly in people with low neutrophil counts; • Antibiotics could save your life, so if you get a fever or feel ill, phone your cancer doctor straight way. When your blood counts are low, your cancer specialist may want you to take antibiotics to help prevent severe infection. Your immune system is very unlikely to be able to fight off an established cancer completely without help from conventional cancer treatment, although there are very rare documented cases of cancers just disappearing (spontaneous regression). Some treatments use elements of the immune system to help treat cancer. Most people feel shocked and upset when they first find out that they have cancer. You may also feel: • Numb; • Frightened and uncertain; • Confused; • Angry and resentful; • Guilty. You may have some of these feelings. Or you may feel totally different. Everyone reacts in their own way. Sometimes it is hard to take in the fact that you have cancer at all. Upsetting feelings are a natural part of coming to terms with cancer. All sorts of feelings are likely to come and go. Your family and friends will probably have strong feelings too. Many people with cancer believe that they should strengthen their immune systems to help beat the disease. There is a commonly held belief that reducing stress can help to strengthen our immune systems. There is some scientific evidence that stress weakens our immunity. While many life stresses cannot be avoided altogether, there are ways of trying not to let things get to you. Many complementary therapies such as meditation, massage and reflexology, can be very relaxing. We can avoid getting run down and look after our self by: • Eating a balanced diet when we are able; • Trying to eat fresh food whenever possible; • Getting plenty of rest - even if we find it hard to sleep, we can rest.