What Causes Cancer

December 2017
The type of cancer that you can get is dependent on where in the body the abnormal cell reproduction begins. There are over 200 types of cancer and there is not one single cause; it is said to be multifactorial.

Common Causes of Cancer

Most cancer types become more common as we age. Less than 1% of cancers are diagnosed in children below 14 years of age, whereas 64% of all new cancer diagnoses affect people over the age of 65 years. This may because some cancers take longer to grow, or that an older person has had more time to be subjected to any of the other risk factors.


Some cancers are more common depending on your gender. In men, prostate cancer is, by far, the most prevalent, causing approximately 25% of cases. This is followed by lung cancer and, then, bowel cancer in third place. The most common cancer in females is breast cancer, which accounts for nearly a third of cases.

Some cancers are more common within families; 5 to 10% of cancers may have a genetic predisposition. If you have more than one family member affected, you may have a higher risk of developing this cancer, and so may be referred by your GP for screening. Genetic testing can help to locate abnormalities in your DNA, which can be passed onto your children. Your GP may refer you to a hospital specialist for further investigation in your DNA, if necessary.

Other Risk Factors of Cancer

Exposure to certain carcinogenic chemicals can cause normal cells to mutate into the abnormal cells that cause cancer. Lung cancer is caused by the most common carcinogen, tobacco smoke.

Cancer can also be caused by exposure to excess radiation, as in tanning beds.

Some diseases or viruses are linked with cancer. For example, Human Papilloma Virus (HPV) is responsible for 95% of cervical cancer, and hepatitis B and C are risk factors for liver cancer.

Change in levels of hormones can increase the risk of cancer. Breast cancer is more common in postmenopausal women, when there are changes in their estrogen levels.

There is more risk of cancer in those patients who have a reduced immune response, e.g. patients who are HIV-positive.

There is evidence that people who have a healthy diet and regularly exercise have a lower risk of developing cancer.

Image: © lightwise - 123RF.com

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Latest update on December 10, 2017 at 01:02 PM by owilson.
This document, titled "What Causes Cancer," is available under the Creative Commons license. Any copy, reuse, or modification of the content should be sufficiently credited to CCM Health (health.ccm.net).
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