Aging & Health A to Z
Causes & Symptoms
Many types of cancer are caused by exposure to carcinogenic (cancer-causing) substances that can be avoided. Often, a change in lifestyle or habits can reduce your risk. Prevention, such as quitting smoking, is critical in reducing your risk of cancer.
Cigarette smoking causes 90% of lung cancers. It is the most obvious example of a habit that raises cancer risk. If you stop smoking, your risk of getting cancer decreases immediately. Eventually, the risk becomes nearly the same as the risk for non-smokers. Smoking is not the only cause of lung cancer, however. A small percentage of people may develop lung cancer even if they don’t smoke, either because there is a family history of the disease or for other reasons that are not yet clear.
Other Types of Cancer
There are other risk factors for certain cancers. These risk factors may be substances, environmental factors, or lifestyle habits, such as:
- chemicals (for example, pesticides)
- excessive consumption of alcohol
- too much sunlight (skin cancer)
- exposure to radiation
- certain viruses (such as those associated with cervical and liver cancer)
For many cancers, the causes remain unknown.
Symptoms and Warning Signs
Cancer symptoms vary depending on the type of cancer, how large the tumor is (if there is a tumor involved), and its location in your body.
Below are symptoms that occur with many cancers:
- Skin changes. Your skin can get darker, itchy, or become red. You can also get jaundice (skin and eyes become yellow).
- Extreme fatigue that doesn’t get better with rest
- Loss of appetite
- Unexplained weight loss
- Night sweats
- Abnormal bleeding, such as red blood in your stool or dark black stools
Never ignore an unusual symptom, especially if it has lasted for a while, or is getting worse. Get checked by a healthcare professional as soon as you can.
Some symptoms, like fatigue, are unlikely to be caused by cancer if it is your only symptom. But it is best to have a check-up, especially if it is worrying you, even if it seems unimportant. Whatever the causes of your symptoms, your healthcare provider will be able to help figure them out and treat them appropriately. And in the unlikely event that it is cancer, the earlier treatment begins, the better.
Updated: February 2018
Posted: March 2012