How is inherited breast cancer different from other genetic diseases?
On average, by the age of 70, women with one of the alterations tested for in this study have about a 50 percent chance of being diagnosed with breast cancer and 16 percent chance of developing ovarian cancer. Men with an alteration have about a 16 percent chance of developing prostate cancer by the age of 70. However, for any individual with an alteration, a precise estimate of risk is not possible. Family history helps to place an individual’s cancer risk in perspective, but is also an imperfect tool. For example, family history will be most useful in determining risk if a carrier has multiple relatives affected with breast or ovarian cancer. In this case, a woman’s risk of breast cancer may be higher than the average of 56 percent. If a carrier has little or no family history of breast and ovarian cancer, his or her risk will be much more difficult to assess. This is particularly true of women in small families with very few close female relatives. Unless someone already has a stron
