Lots of things are known to cause cancer, including smoking or too much exposure to the sun.
Still, some people without any obvious risk facts get one form of the disease or another. The American Cancer Society says sometimes heredity is a factor and genetic testing and family histories can offer insights into possible risks.
But knowing you might be at risk for cancer can cause problems, too. Some people have adopted preventive measures, like taking potent drugs like tamoxifen or having healthy breasts removed, because they faced a higher risk of the disease. Those are drastic steps and only should be considered after a thorough medical evaluation and counseling, the society says.
