What You Should Know
- A major breast cancer study suggests many patients may be able to safely avoid chemotherapy after surgery, allowing them the chance to avoid tough chemo-related side effects like nausea and fatigue.
- The OPTIMA clinical trial used the 50-gene Prosigna test to help identify who is unlikely to get meaningful benefit from chemotherapy, and it found that “about two-thirds of patients whose tumors did not appear to have a meaningful chance of benefiting from chemotherapy.”
- The findings apply to a specific group: people 40 or older with early-stage ER-positive, HER2-negative breast cancer, including some with lymph node involvement.
- This doesn’t mean chemotherapy isn’t important. It simply shows that for some women, a genomic test can help identify when chemotherapy is unlikely to add much benefit, allowing them to safely avoid it.
The OPTIMA clinical trial was designed around that exact question. The large phase 3 study looked at whether testing the tumor for certain genetic markers could help doctors decide which patients with higher-risk, estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 (HER2-negative) early breast cancer could safely skip chemotherapy and receive hormone-blocking treatment instead.
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What OPTIMA Studied
The OPTIMA clinical trial studied people whose breast cancer had already been removed with surgery. Patients were aged 40 or older with ER-positive, HER2-negative invasive breast cancer. Some had cancer in one to nine lymph nodes; others had larger tumors of at least 30mm diameter without lymph node spread.
The trial compared standard treatment, which is chemotherapy followed by endocrine (also called hormone therapy), with a test-directed approach using Prosigna, a 50-gene test that analyzes the biology of the tumor.
The Prosigna test identifies a low-risk threshold, which is a score of ≤60 on the Risk of Recurrence (ROR) scale. Patients with high Prosigna scores above 60 were more likely to receive chemotherapy followed by endocrine therapy, while those with low scores of 60 or less received endocrine therapy alone.
WATCH: Molecular Testing’s Important Role in Determining Treatment for Advanced Breast Cancer
Patients with a higher Prosigna Risk of Recurrence score received chemotherapy plus endocrine therapy. Patients with a lower score received endocrine therapy without chemotherapy. For premenopausal patients, endocrine therapy included ovarian function suppression, which is treatment to lower or shut down estrogen production from the ovaries.
In the OPTIMA results presented at the 2026 American Society of Clinical Oncology (ASCO) meeting, which is the largest cancer conference held annually. The test identified about two-thirds or 68% of high-risk patients whose tumors were classified as low genomic risk and did not appear to have a meaningful chance of benefiting from chemotherapy.
Helping Patients Cope with Chemo Side Effects
What the Results Mean for Patients
The main result was reassuring: the test-directed approach met the study’s standard for non-inferiority, meaning outcomes were close enough to standard chemotherapy-based treatment within a margin the researchers had set in advance.
At the five-year mark, invasive breast cancer-free survival was 91.5% in the standard treatment group and 90.4% in the test-directed group. Among patients with lower Prosigna scores, the five-year rates were 94.9% with chemotherapy plus endocrine therapy and 93.7% with endocrine therapy alone.
That does not mean chemotherapy has no role. It means that, for selected patients, a genomic test may help avoid chemotherapy when the chance of added benefit is very small.
WATCH: Managing Chemotherapy Side Effects
Dr. Layman said the hope is to give treatment where it truly helps, without exposing patients to chemotherapy unnecessarily.
“I also don’t want to be giving the chemotherapy to the patients who are not going to benefit from it,” Dr. Layman said.
She added that this question is deeply personal for patients who are trying to keep working, parenting, and living their lives during treatment.
“These individual women, especially premenopausal women who are young and they are so busy, they’re in their careers, they’re moms, they’re in the peak of their life,” Dr. Layman said.
Why This Is Not a One-Size-Fits-All Answer
Patients should not stop or decline chemotherapy based on a headline. OPTIMA applies to a specific breast cancer population, and decisions still depend on tumor size, lymph node involvement, grade, menopausal status, overall health, prior treatment, and genomic test results.
The trial also does not mean every genomic test gives the same answer in every situation. Patients should ask their oncologist whether Prosigna, Oncotype DX, MammaPrint, or another test is appropriate for their cancer.
Dr. Layman also encouraged patients to seek clarity if they are unsure.
“Your doctor should never be offended if you want to get a second opinion,” Dr. Layman said.
Questions to Ask Your Doctor
- Is my breast cancer ER-positive and HER2-negative?
- Did my cancer involve any lymph nodes? If so, how many?
- Would a genomic test help guide whether I need chemotherapy?
- Which genomic test is most appropriate for my situation?
- If I skip chemotherapy, what endocrine therapy would I need?
- If I am premenopausal, would ovarian suppression be part of my treatment?
- What are the benefits and risks of chemotherapy in my specific case?
- Would you recommend a second opinion before I decide?
Dr. Layman said her broader message to patients is one of cautious hope.
“My message to patients is that we are in a really exciting time right now,” she said. “What we are seeing is an explosion of new treatments and a better understanding of how cancers work.”
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