Cancer, its causes and effects

know because many drugs used to fight cancer attack malignant cells during the active phase. At this accelerated rate, they often begin to form a mass of dividing tissue called a tumour. The tumour is fed by nutrients that diffuse through neighbouring blood vessels and can also grow by forming a substance called tumour angiogenesis, or vessel forming, factor. This factor stimulates the growth of an independent blood supply to the tumour. So that it actually becomes independent to the surrounding blood vessels that it originally utilised.  Tumours can cause destruction in three common ways: firstly tumours put pressure on nearby tissues and/or organs. Also, tumours invade tissues and organs directly, often damaging or disabling them in the process. And finally, tumours make invaded tissues and/or organs susceptible to infection. However, although rare, tumours can also release substances that destroy tissues in close proximity to them.                                                                                         However, it is important to note that not all tumours are cancerous. Tumours can be either malignant or benign. A malignant tumour is cancerous, and a benign tumour is not. One main difference between a benign tumour and a malignant tumour is that a benign tumour will not spread, or metastasize to distant parts of the body, and usually it will not grow back once removed. A benign tumour is either surgically removed, or it may be left in place and simply observed to see what it does. The decision to remove or observe depends on the tumour’s size, type and location.                                                                                                                                           One of the main problems with treating cancer is the possibility of metastasis. This is the process where millions of malignant cells are released from the tumour, where the cancer first developed, into the bloodstream. Fortunately, most of these cells are killed by trauma produced while travelling within the blood vessel walls, or by circulating white blood cells from the immune system, such as the T-cells. Other immune cells that battle malignant cells are macrophages, antigen-presenting cells, and substances produced by immune cells called lymphocytes. In some cases, the circulating malignant cells survive and adhere to the inner muscular lining of the blood vessel walls. Here the process of tumour formation can begin in a different area of the body and cause a secondary tumour, causing further destruction.                                                                 Cancer is caused by a number of factors, some of which we can control, and some we cannot. One of the uncontrollable factors is the presence of gene mutations. One type of gene that plays a role in normal cell growth is called an ontogeny. This can be altered to contribute to the uncontrolled growth of a tumour. Ontogenesis affects the way cells use energy and multiply. For example, in some cancers, the RAS gene, an ontogeny, is mutated, and produces a protein that stimulates cells to divide prematurely.                                                                                                          Mutations in tumour suppressor genes are another common cause of cancer. As you might expect, a tumour suppressor gene is supposed to prevent tumours. But when these genes are damaged, they can allow cancer to develop instead of preventing it. One of these genes, p53, normally prevents cells with abnormal DNA from surviving. When p53 is defective, these cells with abnormal DNA survive and can multiply, increasing the probability of developing cancer.                                                               Certain cancers are associated with chromosomal abnormalities. When genes are missing, duplicated, or rearranged, a predisposition to develop a tumour is increased. Certain leukaemia’s, sarcomas, lymphomas, and others tumours are associated with chromosomal abnormalities.                                                                                                  There are also viruses associated with cancer. The human papillomavirus (HPV) that causes genital warts is associated with carcinoma of the cervix, and the Epstein-Barr virus that causes infectious mononucleosis or glandular fever is associated with Burkett’s lymphoma. Diseases or drugs that affect the immune system can also increase the risk for certain cancers. The disease AIDS, for instance, is associated with a high risk of two types of cancer, namely, Kaposi's sarcoma and lymphoma.                                   Exposure to ionizing radiation can increase the risk of certain cancers. X-rays used to treat disorders such as acne or adenoid enlargement can increase the risk of certain types of leukaemia’s and lymphomas. Fortunately, there are also factors under our control that can increase the risk of getting cancer, and can therefore be avoided. There are substances called carcinogens that can increase the risk of getting cancer. Some common carcinogens include: Arsenic, asbestos, and nickel, which can cause lung and other cancers; Benzene, which can cause leukaemia; Formaldehyde, which can cause nasal and nasopharyngeal cancer; and many others.                                                                                                  Carcinogens that are associated with a person's lifestyle include alcohol, which increases the risk of oral, oesophageal, and oropharyngeal cancer, and tobacco, which causes lung, head and neck, oesophageal, and bladder cancer. Smokeless or chewing tobacco can also increase the risk of oral cancer. Unprotected exposure to sunlight (ultraviolet radiation) is associated with skin cancer. The main cancers caused by sunlight are basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.           However, according to some studies, nearly two out of three people can avoid cancer by not smoking and eating a healthful diet that limits high fat foods and includes generous servings of fruits and vegetables. Other habits that discourage cancer include: Limiting the use of alcohol; Including physical activity into your daily routine; Maintaining a healthy body weight; Reducing environmental exposure to carcinogens and using sunscreen when outside.