The major risk factors for cancer are: tobacco, alcohol, diet, sexual and reproductive behavior, infectious agents, family history, occupation, environment and pollution.
According to estimates of the American Cancer Society (ACS), approximately 40% of cancer deaths in 1998 were due to tobacco and excessive alcohol use. An additional one-third of the deaths were related to diet and nutrition. Many of the one million skin cancers diagnosed in 1998 were due to over-exposure to ultraviolet light from the sun's rays.
According to estimates of the American Cancer Society (ACS), approximately 40% of cancer deaths in 1998 were due to tobacco and excessive alcohol use. An additional one-third of the deaths were related to diet and nutrition. Many of the one million skin cancers diagnosed in 1998 were due to over-exposure to ultraviolet light from the sun's rays.
| Frequency Of Cancer-Related Death | |
|---|---|
| Cancer Site | Number of Deaths Per Year |
| Lung | 160,100 |
| Colon and rectum | 56,500 |
| Breast | 43,900 |
| Prostate | 39,200 |
| Pancreas | 28,900 |
| Lymphoma | 26,300 |
| Leukemia | 21,600 |
| Brain | 17,400 |
| Stomach | 13,700 |
| Liver | 13,000 |
| Esophagus | 11,900 |
| Bladder | 12,500 |
| Kidney | 11,600 |
| Multiple myeloma | 11,300 |
Tobacco
Eighty to 90% of lung cancer cases occur in smokers. Smoking has also been shown to be a contributory factor in cancers of upper respiratory tract, esophagus, larynx, bladder, pancreas, and probably liver, stomach, breast, and kidney as well. Recently, scientists have also shown that second-hand smoke (or passive smoking) can increase one's risk of developing cancer.
Alcohol
Excessive consumption of alcohol is a risk factor in certain cancers, such as liver cancer. Alcohol, in combination with tobacco, significantly increases the chances that an individual will develop mouth, pharynx, larynx, and esophageal cancers.
Diet
Thirty-five percent of all cancers are due to dietary causes. Excessive intake of fat leading to obesity has been associated with cancers of the breast, colon, rectum, pancreas, prostate, gall bladder, ovaries, and uterus.
Sexual and reproductive behavior
The human papillomavirus, which is sexually transmitted, has been shown to cause cancer of the cervix. Having too many sex partners and becoming sexually active early has been shown to increase one's chances of contracting this disease. In addition, it has also been shown that women who don't have children or have children late in life have an increased risk for both ovarian and breast cancer.
Infectious agents
In the last 20 years, scientists have obtained evidence to show that approximately 15% of the world's cancer deaths can be traced to viruses, bacteria, or parasites. The most common cancer-causing pathogens and the cancers associated with them are shown in table form.
Family history
Certain cancers like breast, colon, ovarian, and uterine cancer recur generation after generation in some families. A few cancers, such as the eye cancer "retinoblastoma," a type of colon cancer, and a type of breast cancer known as "early-onset breast cancer," have been shown to be linked to certain genes that can be tracked within a family. It is therefore possible that inheriting particular genes makes a person susceptible to certain cancers.
Occupational hazards
There is evidence to prove that certain occupational hazards account for 4% of all cancer deaths. For example, asbestos workers have an increased incidence of lung cancer. Similarly, a higher likelihood of getting bladder cancer is associated with dye, rubber and gas workers; skin and lung cancer with smelters, gold miners and arsenic workers; leukemia with glue and varnish workers; liver cancer with PVC manufacturers; and lung, bone and bone marrow cancer with radiologists and uranium miners.
Environment
Radiation is believed to cause 1-2% of all cancer deaths. Ultra-violet radiation from the sun accounts for a majority of melanoma deaths. Other sources of radiation are x rays, radon gas, and ionizing radiation from nuclear material.
Pollution
Several studies have shown that there is a well-established link between asbestos and cancer. Chlorination of water may account for a small rise in cancer risk. However, the main danger from pollution occurs when dangerous chemicals from the industries escape into the surrounding environment. It has been estimated that 1% of cancer deaths are due to air, land, and water pollution.
| COMMON PATHOGENS AND THE CANCERS ASSOCIATED WITH THEM | |
|---|---|
| Causative Agent | Type of Cancer |
| Viruses | |
| Papillomaviruses | Cancer of the cervix |
| Hepatitis B virus | Liver cancer |
| Hepatitis C virus | Liver cancer |
| Epstein-Barr virus | Burkitt's lymphoma |
| Cancers of the upper pharynx | Hodgkin's lymphoma, Non-Hodgkin's lymphoma, Gastric cancers |
| Human immunodeficiency virus (HIV) | Kaposi's sarcoma Lymphoma |
| Bacteria | |
| Helicobacter pylori | Stomach cancer Lymphomas |
Cancer is a progressive disease, and goes through several stages. Each stage may produce a number of symptoms. Some symptoms are produced early and may occur due to a tumor that is growing within an organ or a gland. As the tumor grows, it may press on the nearby nerves, organs, and blood vessels. This causes pain and some pressure which may be the earliest warning signs of cancer.
Despite the fact that there are several hundred different types of cancers, producing very different symptoms, the ACS has established the following seven symptoms as possible warning signals of cancer:
- changes in the size, color, or shape of a wart or a mole
- a sore that does not heal
- persistent cough, hoarseness, or sore throat
- a lump or thickening in the breast or elsewhere
- unusual bleeding or discharge
- chronic indigestion or difficulty in swallowing
- any change in bowel or bladder habits
Many other diseases, besides cancer, could produce the same symptoms. However, it is important to have these symptoms checked, as soon as possible, especially if they linger. The earlier a cancer is diagnosed and treated, the better the chance of it being cured. Many cancers such as breast cancer may not have any early symptoms. Therefore, it is important to undergo routine screening tests such as breast self-exams and mammograms.
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