WHAT ARE THE CAUSES OF CANCER?

Cancer – one of the most deadly diseases that inflicted humans develops in almost any organ or tissue of the body, but certain types of cancer are more life-threatening than others. There is still much to be discovered by scientists in understanding the cause of cancer but many studies have shown that many people are prone to develop the diseases than others. Scientists relied heavily on epidemiologists study particularly populations to identify why cancer rates vary. Population studies provide useful information about risk factors that increases the likelihood of developing cancer.
The preeminent causes of cancer are:

1. CARCINOGENS
   One of the greatest risk factors for cancer is prolonged or repeated exposure to carcinogens—chemical, biological, or physical agents that cause the cellular damage that leads to cancer. According to researchers, a substance is called a carcinogen if it causes a significant increase in some form of neoplasm, or anomalous cell growth. Substances indicted as carcinogenic include tobacco smoke, diet, pathogens, radiation, environmental and occupational chemicals including benzene, asbestos, vinyl chloride, aniline dyes, and arsenic, pollutants (DDT, Kepone, and EDB)

a. Tobacco (Smoking)
It is the most lethal of all cancer-caused deaths in the United States and Canada making it the most lethal carcinogen available. Smoking is associated with cancer in the lungs, oesophagus, respiratory tract, bladder, pancreas, and probably cancers of the stomach, liver, and kidneys. The risk of cancer increases depending on the number of cigarettes smoked per day, the cigarette’s tar content, and how many years a person smokes. Starting to smoke while young significantly increases the risk of developing cancer. Additionally, many non-smoking adults die of lung cancer caused by exposure to the smoke of other cigarettes, called second-hand smoke or environmental tobacco smoke.

b. Diet
Diet is also a major contribution to cancer. Fats from red meats, such as hamburger or steak, and high-fat dairy products are linked with several cancers. High salt intake also increase the risk of stomach cancer. Alcohol consumption increases the risk of cancer of the oesophagus and stomach, especially when combined with smoking.

c. Pathogens
Some carcinogens are living organisms. Certain viruses, bacteria, and parasites account for about 15 percent of all cancer deaths in the United States. Cancer-causing viruses include the human papillomavirus (HPV), a sexually transmitted virus responsible for 70 to 80 percent of all cases of cancer of the cervix. Hepatitis B and C viruses cause almost 80 percent of all liver cancer in the world. One of the major causes of cancer in developing countries are parasitic organism.
d. Radiation
Exposure to electromagnetic radiation, invisible, high-energy light waves such as sunlight and X rays, accounts for a small percentage of cancer deaths. Most cancer deaths from radiation are from skin cancer, which is triggered by too much sun exposure. A good example is radon, a colourless, odourless, radioactive gas, seeps from the Earth have been linked to a significant amount of lung cancer cases in the United States and Canada.
e. Environmental and Occupational Chemicals
Air pollution, water pollution, and pollutants in the soil contribute particularly to lung and bladder cancer. Lung cancer rates are generally higher in cities, where increased industry and automobile traffic produce air pollution. Occupational carcinogens include such industrial chemicals as benzene, asbestos, vinyl chloride, aniline dyes, arsenic, and certain petroleum products.

1. HEREDITARY FACTORS
   Hereditary factors has recently been linked to playing a role in the development of cancer. Some gene mutations associated with cancer are inherited. Researchers believe that many other hereditary factors contribute to cancer. In addition to inherited mutations, other genetic variations, particularly those influencing how the body responds to carcinogens, may create a greater susceptibility to cancer. The identities of the majority of these genetic variations are not yet known.

2. STEROID HORMONES
   Cancer of the reproductive organs are caused by naturally-occurring steroid hormones produced by the endocrine system (a group of specialized organs and body tissues that produce, store, and secrete chemical substances known as hormones). These hormones stimulate reproductive organ cells to divide and grow. In women, relatively high or long exposure to the female sex hormone oestrogen seems to increase the risk of breast and uterine cancers.

3. POPULATION DEMOGRAPHICS
   Population studies indicate that a person’s age, race, and gender influence the probability that he or she will develop cancer. Most cancers occur in adults middle-aged or older. The risk of cancer increases as individuals age because genetic mutations accumulate slowly over many years, and the older a person is, the more likely that he or she will have accumulated the collection of mutations necessary to turn an otherwise healthy cell into a cancerous cell. More than three-fourths of all cancers in North America are diagnosed in people over age 55.

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