OPTIMA Trial Shows Promising Results
Many breast cancer patients could potentially avoid chemotherapy through a new gene test. This finding was presented at the American Society of Clinical Oncology meeting in Chicago on 30th May. The OPTIMA trial included over 4,400 participants worldwide, with 263 from Australia and New Zealand.
Significant Findings from the OPTIMA Trial
The trial, designed to reduce unnecessary chemotherapy, focused on tumour biology rather than traditional clinical features. A/Prof Belinda Kiely, Chair of the Australian study, stated, “These findings show that chemotherapy offers little or no additional benefit for people with low Prosigna scores.” This means that a substantial number of patients could avoid chemotherapy and its side effects.
Participants aged 40 and older, who had undergone surgery for hormone-receptor-positive breast cancer, were included in the study. They were randomly assigned to receive either standard chemotherapy followed by hormone therapy or treatment guided by their Prosigna test score.
The trial results revealed that 68% of participants had a low Prosigna score. For these individuals, five-year survival and recurrence rates were nearly the same. Specifically, 94.8% of chemotherapy recipients and 93.6% of those on hormone therapy alone were cancer-free after five years.
Similar outcomes were observed for both pre- and post-menopausal women, suggesting hormone therapy alone might suffice in certain cases. The next phase of OPTIMA will further explore the test’s use for premenopausal women.
Chemotherapy is often prescribed to those with early-stage breast cancer that has spread to nearby lymph nodes. However, the concern is that many with hormone-receptor positive breast cancer receive little benefit from this treatment. The OPTIMA trial addressed this by using the genomic test Prosigna, which measures gene activity involved in cancer growth.
Conducted by Breast Cancer Trials in Australia, the OPTIMA trial’s findings represent a significant advancement toward personalized treatment for breast cancer patients. According to A/Prof Kiely, utilising tumour biology to guide treatment decisions addresses a long-standing challenge in breast cancer care.
The study presented at the 2026 ASCO meeting highlights the potential to transform care for thousands of patients each year by sparing them unnecessary side effects from chemotherapy.
Last updated: 1 June 2026, 3:50 pm
