Diseases and Conditions: What are the Risk Factors of Cancer

• Overview
  
• Symptoms
• Risk Factors
  
• Diagnosis
• Treatment
  

RISK FACTORS

Cancer has no single cause since cancer is not a single disease. Most likely, cancer occurs because of interactions between multiple risk factors or repeated exposure to a single carcinogenic agent. Among the risk factors that have been linked to cancer are heredity, chemical and environmental carcinogens, cancer-causing viruses, and immunologic defects. All cancers result from nonlethal genetic changes that transform a normal cell into cancerous cell.

Heredity:

50 types of cancer can be linked to hereditary predisposition. Breast cancer for example, occurs more frequently in women whose grandmothers, mothers, aunts, and sisters also have experienced a breast malignancy. The genetic predisposition for development of cancer has been documented for a number of cancerous and precancerous lesions that follow mendelian inheritance patterns.
Cancer is found in approximately 10% of persons having one affected first-degree relative, 15% of persons having two affected family members, and 30% of persons having three affected family members. The risk increases to approximately 50% in women 65 years of age who have multiple family members with breast cancer.
Several cancers exhibit an autosomal dominant inheritance pattern. In approximately 40% of cases, retinoblastoma is inherited as an autosomal dominant trait; the remaining cases are nonhereditary.

Chemical and Environmental Carcinogens

More than six million chemicals have been identified. It is estimated that less than 1000 of these have been extensively examined for their carcinogenic potential.
Approximately 2% to 4% of cancer deaths are associated with an exposure to an occupational hazard. For example, exposure to asbestos fibers is significantly related to increased risks for developing several cancers like lung, larygeal and gastrointestinal cancers. Increased incidence of leukemia are associated with benzene exposure.
Many cancers are associated with lifestyle risk factors, such as smoking, dietary factors, and alcohol consumption

Cigarette smoking - contains both procarcinogens and promoters. It is directly associated with lung and laryngeal cancer and has been linked with cancers of the esophagus, pancreas, kidney uterine cervix, and bladder. Chewing tobacco or tobacco products increases the risk of cancers of the oral cavity and esophagus. Not only is the smoker at risk, but others passively exposed to cigarette smoke is at risk.

Diet - examples are benzopyrene and other polycyclic hydrocarbons may be produced when meat and fish are charcoal broiled or smoked or when foods are fried in fat that has been reused multiple times. Nitrosamines, which are powerful carcinogens, may be formed from nitrites added to vegetables and foods as preservatives. Cancer of the colon has been associated with high dietary intake of fat, protein, and beef and low intake of dietary fiber.

Alcohol - modifies the metabolism of carcinogens in the liver and esophagus.

Radiation

The type of cancer depends on the dose of radiation, sex of the person and age at which exposure occurred. The length of time between exposure and the onset of cancer is also related to the age of the individual.
Exposure to sunlight also developed cancer because the ultraviolet radiation emits relatively low energy rays that do not deeply penetrate the skin but the skin absorb most of the rays.

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