Risk factors for cancer
According to World Health Organization (WHO), common risk factors for cancer include:
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Tobacco use
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Alcohol use
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Overweight and obesity
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Dietary factors, including insufficient fruit and vegetable intake
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Physical inactivity
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Chronic infections from helicobacter pylori, hepatitis B virus (HBV),
hepatitis C virus (HCV) and some types of human papilloma virus (HPV)
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Environmental and occupational risks including ionizing and non-ionizing radiation
Cancer-causing agents
Chemical carcinogens
Several chemicals and environmental toxins are responsible for changes
in normal cellular DNA. Substances that cause DNA mutations are known as
mutagens, and mutagens that cause cancers are known as carcinogens.
Particular substances have been linked to specific types of cancer.
Tobacco smoking is associated with many forms of cancer, and causes 90%
of lung cancer. Similarly, prolonged exposure to asbestos fibers is
associated with mesothelioma.
Tobacco is also related to other cancers such as lung, larynx, head,
neck, stomach, bladder, kidney, oesophagus and pancreas as it contains
other known carcinogens, including nitrosamines and polycyclic aromatic
hydrocarbons.
Ionizing radiations
Radiations due to radon gas and prolonged exposure to ultraviolet
radiation from the sun can lead to melanoma and other skin malignancies.
Radiation therapy given for one type of cancer may also cause another
type of cancer. For example, those who receive chest radiation therapy
for lymphomas may later develop breast cancer.
Viral and bacterial infections
Some cancers can be caused by infections with pathogens. Notable among
these include liver cancers due to Hepatitic B and C infections;
cervical cancer due to infections with Human Papilloma virus (HPV);
Epstein Barr virus causing Burkitt’s lymphoma and gastric or stomach
cancer due to Helicobacter pylori infection.
Genetic or inherited cancers
Common examples are inherited breast cancer and ovarian cancer genes
including BRCA1 and 2. Li-Fraumeni syndrome includes defects in the p53
gene that leads to bone cancers, breast cancers, soft tissue sarcomas,
brain cancers etc. Those with Down’s syndrome are known to develop
malignancies such as leukemia and testicular cancer.
Hormonal changes
Notable among these are changes in the female hormone levels estrogen. Excess estrogen promotes uterine cancer.
Immune system dysfunction
Impaired immunity including HIV infection leads to several cancers
including Kaposi's sarcoma, non-Hodgkin's lymphoma, and HPV-associated
malignancies such as anal cancer and cervical cancer.
Thanks to
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