Families with Breast Cancer
Medical Author: Carolyn Janet Crandall, MD, FACP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
Ms. G. is a 40-year-old woman with two small children. Like most women, she is concerned about her chances of developing breast cancer. She asks her doctor about her risks. Although breast cancer is a worry for most women, Ms. G. is especially worried because of a family history of breast cancer. Her mother and sister had breast cancers that were diagnosed at young ages.
A woman with a family history of breast cancer has a lot of concerns. Among other things, she is thinking of her job, children, and husband, as well as how her medical insurance and health team will be able to serve her needs in the future should a crisis arise.
What are the facts about families that have multiple members with breast cancer?
Inherited breast cancer disorders account for a small minority of breast cancers overall. Genes are the "messages" in each cell of the body that determine the ultimate design of our bodies. Genes can be damaged by the environment. Additionally, people can be born with defects in the genes that remove the body's defenses against cancers. Only in about 10% of all breast cancer cases is there actually a genetic defect that can be tested. This means that 90% of breast cancers are due to other causes. In fact, most cases of breast cancer occur in women who do not have a family history of breast cancer. A complex interplay between environmental and genetic factors affect the development of breast cancer, and all the key factors have not yet been identified.