Is cancer hereditary? my maternal grandmother had breast cancer does it mean my mother is going to get it? how likely am i to get it?

Not always: Not always - but do keep an eye out for breast cancer at an earlier age.

Heredity: Heredity only accounts for about 15% of breast cancers. The standard risk of breast cancer of women in the us is about 12% in a lifetime. Having one family member with breast cancer does not mean all will get breast cancer. Have a yearly breast examination with your doctor after age 20, yearly mammogram after age 40, and have breast lumps evaluated by your doctor.

Increased risk: Having a family history of breast cancer does increase your risk, especially when they had it before menopause. You should speak to a genetic counselor to define your risk better for you.