Apart from genetic mutation that increases the risk of breast cancer, presence of a family member with breast cancer would increase the risk of development of breast cancer in a woman. Unlike patients who are carriers of well-recognized genetic mutations, these women do not have any evidence of genetic alterations that would increase the risk of breast cancer. The increased breast cancer risk in this group of women may be caused by a group of genes, which has increased predisposition to development of breast cancer. It is also difficult to separate environmental factors in these patients and how much of this increased risk is caused by common environmental factors is difficult to judge. If a woman, say Miss D has a first degree relative
(mother, daughter, or sister) with diagnosis of breast cancer, the risk of Miss D developing breast cancer is 1.7 times higher (called relative risk) compared to the general population. If that first-degree relative of Miss D had developed breast cancer prior to the menopause, the relative risk for Miss D would be 3 fold. On the other hand if that relative had breast cancer after menopause, the relative risk for Miss D would be 1.5 fold. If that relative had developed bilateral breast cancer then the relative risk for Miss D would be 5 fold higher. Again if that relative who developed bilateral breast cancer had developed the breast cancer prior to menopause, the relative risk for Miss D would be 9 fold higher.