When is a genetic cause of cancer suspected?

Family history is one of those risk factors that we can do absolutely nothing about, but knowing what you might be up against is key to ramping up a plan of protection. A family history of cancer is suspected when several members are affected -- sometimes at younger ages -- or when members have multiple or unusual types of cancer.
This content originally appeared on doctoroz.com

When many cases of cancer occur in a family, it is most often due to chance or because family members have been exposed to a common toxin, such as cigarette smoking. Less often, these cancers may be caused by an inherited gene mutation. (These are called family cancer syndromes.) Certain things make it more likely that an abnormal gene is causing cancers in a family, such as

• Many cases of a rare type of cancer (like kidney cancer)
• Cancers occurring at younger ages than usual (like colon cancer in a 20 year old)
• More than one type of cancer in a single person (like a woman with both breast and ovarian cancer)
• Cancers occurring in both of a paired organ (both eyes, both kidneys, both breasts)
• More than one childhood cancer in a set of siblings (like sarcoma in both a brother and a sister)