OPTIMA Trial Supports Gene Test Triage, Some Breast Cancer Patients May Avoid Chemotherapy

New results from the international OPTIMA clinical trial show that, for hormone receptor-positive breast cancer, using the Prosigna gene test to support treatment decisions may allow a substantial proportion of patients to avoid chemotherapy without clearly compromising short- to medium-term efficacy.

The study enrolled more than 4,000 newly diagnosed breast cancer patients, with participating regions including the United Kingdom, Northern Europe, Australia, New Zealand, and Thailand. The trial compared the traditional approach of recommending chemotherapy based on clinical risk with a strategy of first stratifying patients through tumor gene expression testing and then deciding whether to add chemotherapy.

Prosigna is a test that analyzes the activity of 50 genes in tumor tissue and can provide a score related to recurrence risk as well as molecular subtype information. Under the trial design, patients with higher test scores still received chemotherapy plus hormone therapy; those with lower scores could forgo chemotherapy and instead receive mainly hormone therapy, while other necessary treatments such as radiotherapy were arranged as usual.

Preliminary results showed that, among the population triaged by gene testing, the proportion of low-score patients who were alive and had no breast cancer recurrence within five years after omitting chemotherapy was very close to that of patients who received chemotherapy plus hormone therapy. This suggests that, for some patients with lower biological risk, the additional benefit of chemotherapy may be limited.

If subsequent data and peer review support these conclusions, OPTIMA may affect clinical guidelines and discussions about healthcare reimbursement. Postoperative breast cancer treatment has long relied on information such as tumor size, lymph node status, and pathological features; the role of gene testing is to try to add another layer of judgment about the tumor's actual tendency to recur.

However, these results still need to be interpreted with caution. The trial mainly applies to hormone receptor-positive breast cancer and cannot be directly extrapolated to all breast cancer subtypes; although male patients participated, their number was insufficient to draw robust conclusions. In addition, current reporting focuses on five-year results, and the full data are still needed to clarify long-term recurrence and the real-world benefits across different age groups and different healthcare systems.

For patients, this is not a basis for independently choosing to stop or refuse chemotherapy, but rather an indication that precision testing may allow physicians and patients to have more individualized discussions about risk, efficacy, and side effects. Whether it can actually be adopted still depends on test accessibility, insurance or public reimbursement, and how local guidelines assess the strength of the OPTIMA evidence.