If one of the sisters has breast cancer, should the other sisters be screened? If one of the sisters has breast cancer, should the other sisters be examined? Clinical and epidemiological investigations have found that the occurrence of breast cancer is related to genetic factors. Women with a family history of breast cancer have two to three times the chance of developing breast cancer as compared to normal women, and women with a family history of bilateral breast cancer have six to nine times the chance of developing breast cancer as compared to normal women, and this predisposition is not only related to the mother, but also to the father. Therefore, when someone in the family has breast cancer, it is necessary for other sisters to be examined.