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Genetic Testing for Breast Cancer: Positive but Proactive

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It’s one of the first questions you’re asked at a mammogram or doctor’s appointment. “Do you have a family history of breast cancer?” For women with close relatives who’ve been diagnosed with breast cancer, this question carries a lot of weight.

Having a close female relative–sister, mother, daughter–with breast cancer doubles the chances of a woman getting breast cancer, and if two close relatives battled the disease, the risk is five times higher. Often, a strong family history of breast cancer is linked to having a genetic mutation and testing can help.

What Is Genetic Mutation?
Three of the most well-known genes are BRCA1, BRCA2 and PALB2. The function of the BRCA and PALB2 genes is to keep breast cells growing normally and prevent cancer cell growth. But sometimes these genes contain mutations, abnormal changes in a gene that can ultimately cause cancer. Mutations can then be passed through generations. About one of every 400 people carries a mutated BRCA gene.

Women can inherit a mutation from their mothers or fathers and have a much higher chance of developing breast cancer and/or ovarian cancer. Men with mutations also have an increased risk of breast cancer or prostate cancer. Abnormal BRCA1, BRCA2 and PALB2 genes may account for up to 10 percent of all breast cancers, or one in ten cases.

Genetic Testing for Abnormal Genes
While the majority of people who develop breast cancer have no family history of the disease, women with a strong family background have reason to be concerned. If one parent has a BRCA mutation, the chances of inheriting it is about 50 percent, so some people opt to undergo genetic testing to find out. 

Since the overall odds of BRCA mutations are so low, experts recommend only people with a greater risk get tested. Also, insurance companies will cover counseling and testing only for those with increased risks. A person could be considered at high risk for BRCA mutations if they any of the following in their family history: 

• Diagnosed with breast cancer before age 50
• Male breast cancer at any age
• Multiple relatives on the same side of the family with breast cancer
• Multiple breast cancers in the same woman
• Both breast and ovarian cancer in the same woman
• Ashkenazi Jewish heritage; people of Ashkenazi Jewish descent have a 2.5 percent chance of inheriting a BRCA mutation, or about ten times the rate of others.

How Does Genetic Testing Work for Breast Cancer?
A doctor may recommend that affected patients see a genetic counselor to discuss whether genetic testing is an option. This involves giving a blood or saliva sample that can be analyzed to pick up any abnormalities in these genes. But the testing and results are not fully conclusive. 

For instance, a test result can be positive, meaning that the patient does carry the gene mutation, but a negative test indicates that they do not have that particular gene mutation. It does not, however, rule out the possibility of having mutations in other genes. It also does not exclude the chances of developing breast cancer. 

Another challenge with testing is that results can be vague or ambiguous. An ambiguous result means that a mutation has been found on the gene, but it is unclear whether that particular mutation will influence the chances of getting breast cancer.

What to Do with Test Results
Once genetic testing is complete, a patient usually meets with her genetic counselor to clarify what the results mean. Since the results can either be positive, negative or ambiguous, a genetic counselor and a patient’s doctor can help navigate the many decisions that can impact a patient’s life moving forward. Experts stress that early detection is extremely valuable for a patient’s breast cancer defense. The five-year survival rate for breast cancer detected in the early localized stage is over 98 percent, so being proactive is emphasized.

After a positive genetic test result, patients will generally start screenings at a younger age than other women and do them more frequently. Their doctor may also recommend undergoing various types of screenings, such as ultrasounds or MRIs. Although it’s considered a bit more extreme, women with high-risk BRCA mutations may choose to undergo preventive surgery such as a bilateral mastectomy to help further reduce their risks. 

Understandably, people who have tested positive for BRCA1, BRCA2 or PALB2 can be full of emotions. Having genetic mutations does significantly increase the chances of breast cancer, but many people never develop breast cancer at all. For those who do, having an early diagnosis and proper treatment increases their chances of beating the disease while helping predict the health and future of their families. With early discovery and detection, most people go on to survive breast cancer and lead full and normal lives.

Sources: breastcancer.org and nationalbreastcancer.org.