A Letter to a Primary Care Provider (PCP) From a Cancer Genetic Counselor

A Letter to a Primary Care Provider (PCP) From a Cancer Genetic Counselor By: Colette Hyatt, MS, LCGC

Dear PCP, I know you have a very busy day focusing on all areas of your patient’s health, however I would like to bring your attention to inherited risks for cancer. As a primary care doctor, you are the quarterback for all your patients’ healthcare needs and that includes making sure they are doing the right cancer screening based on their cancer risk.

I am sure you are aware of the stats that 1 in 8 women are diagnosed with breast cancer and it is the most common cancer in women (besides skin cancer).1 Since breast cancer is so common, it is something that most of your patients will have a connection to; either themselves or a close family member may have had a diagnosis of cancer. Your patients have probably asked: “Am I doing the right screening for breast cancer?” or “What does my family history mean for my cancer risk?” It is important for patients to be informed about if they are doing the right cancer screening based on their risk for cancer.

While everyone immediately thinks of the guidelines for mammograms, a critical step in making sure your patients are doing the right cancer screening is to determine if they have an inherited risk for cancer. Inherited cancer is rare and only accounts for 5 to 10% of breast cancer cases. Most cancer is what we call sporadic or is something that occurs by chance. Some cancers run in families but might be a shared component of environmental, lifestyle and genetic factors. But for those with an inherited risk, early detection is critical for their care planning.

You may be wondering….

When is genetic testing right for patients? And not just women!

You want your patients to have the right genetic test. An important component of determining the right genetic testing for your patients is family history intake. There is no “one size fits all” genetic testing for

inherited cancer risk. A proper family history intake ensures you can determine the right tests to order and can also help with the interpretation of the genetic testing results when they are returned.

Genetic testing for inherited risk of breast cancer is also something that should be offered to your male patients. Men can get breast cancer, and this can be increased when a man has an inherited risk for cancer. Also, some genes that have breast cancer risk can also have an increased risk of prostate cancer for men.

What do I do with genetic testing results?

If your patient is positive for a genetic mutation or pathogenic variant, it will depend on the particular gene and mutation that was seen to determine what screening or possible surgical options would be recommended for your patient. Referral to genetic specialists, such as a genetic counselor can help review positive test results and determine appropriate care paths. Multi-gene testing has changed the approach of testing patients for inherited cancer risk. Multiple genes are analyzed at the same time and can provide more information for the patient and their families.

The more well-known genetic mutations associated with breast cancer risk are the BRCA1 and BRCA2 genes.3 These genes are associated with hereditary breast and ovarian cancer syndrome (HBOC). HBOC is associated with increased risk for woman of breast cancer, ovarian cancer, melanoma and pancreatic cancer. For men, there is an increased risk of male breast cancer, prostate cancer, melanoma and pancreatic cancer.

If a woman is found positive for a BRCA1 or BRCA2 genetic mutation this will change her cancer screening.3 The highest cancer risk with a BRCA1 and BRCA2 genetic mutation is breast cancer which is estimated to be a 41% to 90% lifetime risk compared to the general population risk of around 12% lifetime risk. 3 A woman would want to start her breast screening at age 25 or sometimes younger if there is young breast cancer in the family. Between age 25 to age 29, this would be breast MRI, age 30 and older this would be mammogram and breast MRI screening. Women should also consider the option of risk-reducing mastectomy due to the high risk of breast cancer.

A positive genetic result would also change her cancer screening and management for other cancer risks. A woman who is positive for a BRCA1 or BRCA2 mutation would have an increased risk of ovarian cancer which is estimated to be 8% to 62% lifetime risk compared to general population risk of around 1-2%. Due to this increased risk of ovarian cancer, it would be recommended to consider risk-reducing sapling o-oophorectomy (RRSO). Recommendations on timing are dependent on whether the patient has a depends on if a BRCA1 or BRCA2 mutation.

For men, there is also a risk of male breast cancer. It would be important to start breast self-exam training and education at age 35 and for a clinical breast exam every year. 3 Men will also want to start their prostate cancer screening at a younger age.

There are more genes to test for than BRCA1 and BRCA2 that have an association with breast cancer risk.3 Some genes have more of a moderate risk of breast cancer while others have more of a high risk similar to BRCA1 and BRCA2.3 Other genes routinely tested for, have early or conflicting evidence of breast cancer risk. Not every gene should be treated the same as cancer risks are different.4 Knowing the risk will help you and your patients understand the proper cancer screening steps.

It is also not only breast cancer associated with these gene mutations. Some of these genes have higher cancer risk associated with them than others.

What about variants of uncertain significance (VUS)?

Uncertain genetics findings can be seen around 33 to 40% percent of the time when doing multi-gene genetic testing for inherited cancer risk.5 This finding is called a variant of uncertain significance or VUS for short. What should you do if your patient brings you a genetic testing result that has a variant of uncertain significance? VUS results should not be used in cancer screening recommendations for your patients. It's important to know that VUS results are treated as negative (or uninformative) until we learn elsewise. Of the VUS results that get reclassified, around 90 percent get reclassified over time to being benign or not associated with disease risk.

What are the next steps after genetic testing?

It is important to understand that knowing cancer risk does not end with genetic testing. While the cancer risks associated with a gene mutation can be high, inherited gene mutations account for only a small percentage of breast cancer. Family history is important for both men and women to know for their cancer risk. Your patients need to be aware of family history in both their maternal and paternal family.

Also remember that family history and genetic testing technology is dynamic. It is important to continue to check in with your patients about updates to family history and remember if they had testing years ago it might be time for them to update to more comprehensive testing.

Thank you for all the work you do for your patients. I look forward to working with you to help keep your patients living their best life possible!

Sincerely, Cancer Genetic Counselor