The Breast Cancer Gene

Cancer is a common disease. All of us start with about a 1 in 3 (30%) chance of developing cancer over the course of our lives. In this country, women have a 1 in 8 (12%) chance of developing breast cancer and about a 1 in 70 (1%-2%) chance of developing ovarian cancer over the course of their lifetime.

Cancer can cluster in a family for several reasons including shared environmental exposures, similar lifestyles, and chance events. Only about 5%-10% of all cases of ovarian or breast cancer are strongly inherited. Usually (but not always), a specific pattern of cancer in the family is seen: young women with cancer, several women with these cancers, and some women with more than one primary cancer. An inherited factor, or altered gene, can be responsible for the pattern of cancer in these families. Genes are units of inheritance made of DNA (which is like a 4-letter chemical alphabet). An alteration (change) in the DNA pattern can be inherited from a parent like other family traits, and can cause an important protein to be missing or not working.

Alterations in ‘cancer predisposition genes’ lead to an increased risk to develop certain types of cancer.

The two most common types of inherited breast and ovarian cancer are BRCA1 and BRCA2.

"Red Flags" for Hereditary Breast and Ovarian Cancer Syndrome include:

  • Breast cancer before age 50
  • Ovarian cancer at any age
  • Male breast cancer at any age
  • Multiple primary cancers
  • Eastern Ashkenazi Jewish ancestry
  • Relatives of BRCA mutation carrier