How does tumor genomic testing differ from genetic testing?

Question

Hello doctor,

I was diagnosed with stage 2 invasive ductal breast cancer, and my oncologist recommended genomic testing to guide treatment. My mother had breast cancer at the age of 48, and my aunt had ovarian cancer at the age of 50, suggesting hereditary risk. My pathology showed a tumor of 3.4 centimeters, estrogen receptor (ER)-positive (88 percent), progesterone receptor (PR)-positive (75 percent), human epidermal growth factor receptor 2 (HER2)-negative, and Ki-67 32 percent.

My oncologist mentioned Oncotype DX recurrence score testing and germline breast cancer gene (BRCA) testing.

What is the difference between tumor genomic testing and inherited genetic testing?
What does Oncotype DX measure?
Will results determine if I need chemotherapy?
What is a good versus bad recurrence score? Should I test for breast cancer gene 1 and breast cancer gene 2 (BRCA1/2)?
What if I am BRCA positive?
Should my daughters be tested?
Will this affect their insurance, and are there other genetic mutations to test?

Kindly help.

Answer 1

Hello,

Welcome to icliniq.com.

I understand your concern.

I am really sorry to hear that you have been diagnosed with breast cancer, and I also understand that there is a family history of breast and ovarian cancer. That makes you more anxious and worried, but I want to reassure you that there is good news, as your cancer is at an early stage (stage 2), which means we can control it very well and treat it successfully.

First, I would like to explain about the genetic tests and what each one means. There are two main types of tests:

Oncotype DX test – This test is done on the deoxyribonucleic acid (DNA) of the cancer cells taken from the tumor itself. It helps us know if the tumor is aggressive or not. Based on the result (the score), we decide whether chemotherapy is needed. If the Oncotype DX score is high, we usually give chemotherapy after surgery.

Breast cancer gene (BRCA) genetic test – This test is done when there is a family history of breast or ovarian cancer, as you mentioned with your mother and aunt. It checks if there is a genetic mutation that runs in the family. If the BRCA test is positive, it means there is a higher chance of developing breast or ovarian cancer, about a 50 percent risk for breast cancer and around 10 percent for ovarian cancer. If your BRCA test is positive, we may sometimes use special medicines called poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors, especially if the disease develops at any stage.

For your daughters, if they are over 25 years old and your BRCA test is positive, it is important that they also do the same test. Depending on their results, we can choose the best preventive plan for each of them to reduce the risk of breast or ovarian cancer in the future.

You also mentioned that your tumor is estrogen receptor (ER)- positive, progesterone receptor (PR)- positive, and human epidermal growth factor receptor 2 (HER2)- negative. This is a non-aggressive type, which is good news. You will need hormonal therapy in some cases for five years, and in others for ten years. Because you have a strong family history, I recommend continuing the hormonal therapy for ten years. The side effects of hormonal therapy are usually mild and well-controlled, so please do not worry.

Hopefully, you will not need chemotherapy, and your treatment will go smoothly and easily. If you ever have any questions, I am always here to support you.

The investigations to be done include genomic tests. The treatment plan will involve surgery followed by hormonal therapy. You are advised to come for a follow-up after seven days.

I hope you are satisfied with my answer. For further queries, you can consult me at iCliniq.

Thank you.