Chicago Center for Jewish Genetics Disorders - Cancer Genetics

Sporadic Cancer

The vast majority of cancers, around 80%-85%, are sporadic, which means that they are not inherited. This might be due to DNA damage at some point in a person's lifetime that is not repaired or is repaired incorrectly. Damage can occur due to several environmental or external (not genetic) causes such as:

Age: The older a person is, the more likely they are to develop cancer. Cancer occurs predominately in people over 50 years of age.
Diet: there is evidence that a high-fat, high-cholesterol diet may increase the risk to develop certain types of cancer, especially colon cancer.
Obesity: Obesity may contribute to a higher risk to develop cancer.
Smoking: Cancer has been definitively linked to smoking, even among non-smokers inhaling secondhand smoke.
Long-term exposures to chemicals: Certain chemicals, such as asbestos, radon, and benzene, have been associated with increased cancer risk with long-term exposure.
High-level radiation exposure: High-level radiation exposure has been associated with a higher likelihood of cancer.
Ultraviolet ray (sun) exposure: Melanoma and other skin cancers have been definitively linked to sun exposure.
Viruses: Hepatitis B and C, human papillomavirus (HPV), and Epstein-Barr virus have been associated with an increased risk of certain kinds of cancer.
Alcohol: Consumption of large amounts of alcohol on a regular basis has been associated with an increase risk of cancer development.
Hormonal history: An increased risk of breast cancer is associated with a longer lifetime exposure to estrogen influenced by such factors as:
- Earlier onset of menstruation (before 12 years of age)
- Later age of menopause (after 55 years of age)
- First live birth after 30 years of age
- Nulliparity (never giving birth)
- Oral contraceptive use

Although the above factors should be taken into account when considering risk, many aspects affect the development of cancer. A person who avoids the above items still might develop cancer, while an individual who indulges in them all might never develop cancer. These factors only moderately modify an individual's risk. Even more difficult to prove are the benefits of certain behaviors, such as exercise, a low fat-diet, breastfeeding, etc, for a decreased risk of certain cancers. In general, a healthy lifestyle is recommended.

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