The exciting trial was discussed at ASCO’s annual meeting.
Key Takeaways
- Some people with high-risk breast cancer may be able to safely forgo chemotherapy thanks to a genomic test developed based on BCRF work, according to a new study.
- The study, known as the OPTIMA trial, showed adding chemotherapy to endocrine therapy provided no added benefit to some patients with high clinical risk.
- The trial results shed important light on premenopausal women receiving ovarian function suppression.
Scientifically reviewed by Priya Malhotra, PhD
Some women with high-risk, ER-positive, HER2-negative early breast cancer may be able to safely avoid chemotherapy, according to results from the OPTIMA trial presented at the 2026 American Society of Clinical Oncology (ASCO) annual meeting.
The phase 3 trial evaluated people with this type of breast cancer who had up to nine positive lymph nodes or a tumor size of at least 30 mm. Historically, many of these patients would routinely receive chemotherapy because of their high clinical risk of recurrence. But a genomic test called Prosigna helped determine that 68% of these patients may safely avoid chemotherapy due to their tumor biology.
Prosigna—which was developed based on studies supported by the Breast Cancer Research Foundation (BCRF)—analyzes the activity of 50 genes and generates a Risk of Recurrence (ROR) score. Notably, the genes that are evaluated using Prosigna differ from those evaluated by other genomic assays, providing valuable information specifically about the biology of the tumors, for example whether they are luminal A or B, basal, or HER2.
Researchers found that Prosigna could help identify a large population of patients that would obtain minimal, if any, benefit from chemotherapy and could therefore avoid it.
Outcomes remained very similar, whether or not patients were on chemotherapy (all patients underwent endocrine therapy): After five years, 90.3% of patients in the Prosigna-guided group remained cancer free; 91.8% of patients in the standard chemotherapy group.
Chemotherapy can be associated with significant short- and long-term side effects. Findings like these help doctors better identify which patients may benefit from chemotherapy—and which may be able to safely avoid it.
This is important because previously, genomic tests have primarily helped identify lower-risk patients who may not need chemotherapy. Landmark studies—including the BCRF-supported TAILORx, RxPONDER, and MINDACT—showed that some patients with ER+/HER2- breast cancer may safely forgo chemotherapy based on a different type of genomic tests, Oncotype DX or MammaPrint. But many patients with significant lymph node involvement or larger tumors were still considered strong candidates for chemotherapy. This trial may change that.
OPTIMA also provided important new evidence for premenopausal women. Researchers found that the Prosigna test could help safely guide chemotherapy decisions in women 40 and older receiving ovarian function suppression, which stops the ovaries from making the estrogen that fuels hormone receptor-positive cancers. This is a significant development, as previously, limited evidence has supported gene tests in younger, premenopausal women.
The study is an important step towards expanding personalized treatment. Donate to BCRF today to help fuel research to find a cure.
