Hereditary Breast and Ovarian Cancer – The causes, the warning signs, and the preventative options that are available.
Approximately 5-15% of all breast and ovarian cancers are due to hereditary factors. Hereditary breast and ovarian cancer is caused by one or more of a number of inherited gene mutations that results in a higher risk of developing these types of cancer.
What causes it?
Certain gene mutations are passed down through generations that increases the risk for developing breast or ovarian cancer.
There are many types of genetic mutations, but the most common are known as BRCA1 and BRCA2 (short for BReast CAncer). These are the gene mutations that people are most familiar with, says Dr. Julia Sun, a physician with the Allard Hereditary Breast and Ovarian Cancer Clinic. “Everyone is born with the BRCA genes, but in certain individuals the gene is mutated. That mutated gene is passed down.”
How is it inherited?
The mutated genes are inherited in an autosomal dominant pattern, which means that if one parent has the mutation, there’s a 50% chance their offspring will inherit the mutation. Not everyone who carries or inherits the gene will develop cancer, though.
How is it identified?
Usually, your family doctor will make the initial identification that you may carry hereditary breast or ovarian cancer genes. This is typically based on the presence of a significant family history of breast or ovarian cancer. For example, if someone in your family was diagnosed with breast cancer at a young age, or there have been family cases of male breast cancer, bilateral breast cancer, or ovarian cancer, this may signal to your physician that there could be a hereditary component to be investigated.
If your physician suspects you may be at risk for hereditary breast or ovarian cancer, then genetic testing may be recommended to determine if you carry mutated genes. Usually, genetic testing starts with an affected individual in your family; if they test positive for the gene, you may also require testing. For example, if your mother has breast cancer and your physician suspects this may be a ‘red flag’, your mother would be genetically tested first to see if she carries the responsible genes.
Can you prevent these cancers even if you have the gene?
If genetic testing shows that you carry a mutation, there are ways to reduce the risk of developing hereditary breast or ovarian cancer. These include increased screening or risk-reduction options.
If you are a carrier, you will likely require more screening meant to pick up signs of breast cancer at an earlier stage. For high-risk individuals, this means that in addition to annual mammogram and self-checks, a yearly MRI would be added to breast screening.
Depending on your family history and if you tested positive for genetic mutation, another option may be preventative surgery. For breast cancer, this could include a prophylactic bilateral mastectomy – removal of both breasts. For ovarian cancer, it could be a salpingo-oophorectomy – removal fallopian tubes and ovaries.
Chemoprevention, which is the use of drugs to stop or keep cancer from developing, may also be an option.
Dr. Sun notes that lifestyle factors – such as eating healthily and exercising – also play a role in cancer risk reduction.