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Are the so-called “breast cancer genes” (BRCA1 and BRCA2) the only two that increase breast cancer risk? And are they always inherited on the mother’s side?

You can inherit mutations in the genes known as “BRCA1” or “BRCA2” from either your mother’s or your father’s side of the family. Normally, BRCA1 and BRCA2 function as tumor suppressor genes, producing proteins that help repair any damage to your cells’ genetic information and suppress abnormal cell growth. When a BRCA1 or BRCA2 gene has a mutation, or a “misspelling” in the letters of the genetic code, this repair function is usually lost—increasing the risk for breast, ovarian, and some other cancers.

In some families, multiple cases of breast and/or ovarian cancer cannot be traced back to the BRCA1 or BRCA2 genes. Researchers are now searching for other inherited genetic mutations that may be responsible for increased risk.

Regardless of family history, you also may be considered to be at higher-than-average risk for breast cancer if you:

  • Had radiation therapy to the chest for treatment of a past cancer
  • Have had previous breast biopsies (examination of surgically removed tissue under a microscope) that detected atypical hyperplasia (fast-growing cells)
  • Have been diagnosed with ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS). These conditions are considered to be “pre-cancers” because they stay in place and do not spread to surrounding tissues.

Reviewed by Jill Stopfer, MS

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What does a formal risk assessment involve?

This process typically involves working through the following series of steps with a genetic counselor:

  • Education about breast and ovarian cancer and the factors that increase and decrease risk
  • Analysis of your family tree, showing the pattern of cancer in your family—who was affected and their ages at diagnosis
  • Education and counseling about genetic testing options (a blood test for inherited mutations in the genes known as BRCA1 and BRCA2)
  • Genetic testing, if appropriate
  • Discussion of the test results
  • Further counseling about special screening and risk-reduction options, if you are found to be high risk.

Reviewed by Jill Stopfer, MS

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I have a couple of relatives who have been diagnosed with breast cancer. Does that automatically mean I am at high risk?

Not necessarily. It really depends on the pattern of cancer in your family. Your doctor may suspect Hereditary Breast and Ovarian Cancer Syndrome—the name given to inherited risk for these diseases—based on the following criteria:

  • Two or more family members on the same side (your mother’s or father’s) have been diagnosed with breast and/or ovarian cancer.
  • One or more cases of these cancers were diagnosed before age 50. (Because most cancers develop later in life, younger diagnosis suggests the possibility of inherited risk.)
  • Your affected relative(s) is your first-degree relation (mother, sister, daughter).
  • Any relative had cancer more than once, had breast cancer in both breasts, or has had both breast and ovarian cancer.
  • You are of Eastern European Jewish ancestry and have had breast or ovarian cancer, or a history of breast or ovarian cancer in close relatives.
  • A close relative has had male breast cancer.

To fully understand whether or not you might be “high risk,” you need to go through a formal risk assessment process with a genetic counselor, a health professional specially trained to provide information and advice about inherited conditions.

Reviewed by Jill Stopfer, MS