Does tumor genomic testing guide breast cancer treatment?

Question

Hello doctor,

I am a 46-year-old woman, recently diagnosed with stage II breast cancer. My tumor is ER+, PR+, and HER2 negative. There are no known BRCA mutations in my family, although my mother had ovarian cancer at the age of 58.

My oncologist suggested genetic profiling of the tumor for targeted therapy options. I have already had surgery and am now waiting for the adjuvant treatment decision. My laboratory results show a normal complete blood count (CBC) and normal liver and kidney function. The PET-CT showed no metastasis. The test is very costly. Will it really change the treatment choice for me? How often does cancer genome testing actually guide therapy in breast cancer?

Kindly help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I read your query and understood your concern.

In your situation, such as stage II, estrogen receptor/progesterone receptor (ER/PR) positive, human epidermal growth factor receptor 2 (HER2) negative breast cancer, post-surgery with no distant spread, the most important decision now is whether you need chemotherapy in addition to endocrine therapy.

For this, doctors recommend tumor genomic assays (such as Oncotype DX, MammaPrint, or Prosigna), which analyze the activity of certain genes in the tumor to predict the risk of recurrence and the likely benefit of chemotherapy. These tests do not look for inherited mutations like the breast cancer gene (BRCA), but rather the tumor’s biology.

In women with estrogen receptor (ER) positive and human epidermal growth factor receptor 2 (HER2) negative early breast cancer, these assays can meaningfully change treatment. Many patients with a low genomic risk score can safely avoid chemotherapy, while those with a high score benefit from adding it.

Studies suggest that genomic profiling alters treatment recommendations in about 20 to 30 percent of cases in this setting, mostly by sparing women from unnecessary chemotherapy. Broader next-generation sequencing (NGS) panels that look for rare mutations are less commonly helpful in early breast cancer, as truly actionable mutations are rare outside of clinical trials. So, while the test is costly, in your case, it can be very useful in guiding whether chemotherapy is needed on top of hormone therapy, and that is why your oncologist is recommending it.

I hope that this answers your query.

Kindly follow up if you have more doubts.

Thank you.