In simple terms; cancer is the overgrowth of cells without control.
This contradicts how normal cells react; as normally cells follow an orderly path that consists of growth; division and programmed cell death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike normal cells, cancer cells do not experience apoptosis; instead they continue to grow and divide. This leads to a mass of abnormal cells that grow without control. There are various types of cancers and the causes differ. I will mention some of the general causes of cancer: (A) GENETICS AND CANCER The family history, inheritance and genetics play an important role in some childhood cancers. Having close relatives in the family can increase the chance of developing cancer. For example; breast cancer and cancer of the ovaries. Genes are the basic carriers that have all the information of your hair colour and skin colour. There are two types of genes: cancer suppressor genes and cancer causing genes. Proto-oncogenes are the "good" genes that normally control what kind of cell it is and how often it divides. When a proto-oncogene mutates (changes) into an oncogene, it becomes a "bad" gene that can become permanently turned on or activated when it is not supposed to be. When this happens, the cell grows out of control, which can lead to cancer. (B) CARCINOGENS A carcinogen is something that can help to cause cancer. Tobacco smoke is a powerful carcinogen. But not everyone who smokes gets lung cancer. Carcinogens are chemicals that can act or help to increase your chance of getting cancer. Carcinogens are present in processed foods drinks, polluted air etc. The list of chemicals in carcinogens is ever increasing. ( C) AGE Most types of cancer become more common as we get older. This is because the changes that make a cell become cancerous in the first place takes a long time to develop. There has to be a number of changes to the genes within a cell before it turn into a cancer cell. These changes can happen by accident when the cell is dividing. It can also happen because the cell has been damaged by carcinogens where the damage has been passed on to newer cells when that cell divides. The longer we live, the more time there is for genetic mistakes to happen in our cells. ( D) IMMUNE SYSTEM People who have problems with their immune systems are more likely to get some types of cancer. This group includes people who:
The types of cancers that affect these groups of people fall into 2 overlapping groups: 1) Infectious causes: They can help cause some cancers but this does not mean that these cancers can be caught like an infection. Viruses: What happens is that the virus can cause genetic changes in cells that make them more likely to become cancerous. Examples of cancers caused by viruses are: a) cervical cancer and other cancers of the genital or anal area that are caused by the Human papilloma virus (HPV). b) some lymphomas c) primary liver cancer: Hepatitis B and C viruses Bacteria: Bacterial infections have not been thought of as cancer causing agents in the past. But studies have shown that people who have helicobacter pylori (H pylori) infection of their stomach develop inflammation of the stomach lining, which increases the risk of stomach cancer. 2) Lymphomas: chronic infections or transplanted organs can continually stimulate cells to divide. This continual cell division means that immune cells are more likely to develop genetic faults and develop into lymphomas.
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