An international study suggests that many women with early-stage breast cancer can safely skip chemotherapy without affecting their chances of successful treatment. The findings come from the OPTIMA clinical trial, which tested whether a genomic test could identify patients who truly benefit from chemotherapy.
The study included over 4,400 participants aged 40 and above from six countries: the United Kingdom, Norway, Sweden, Australia, New Zealand, and Thailand. Most had hormone-sensitive breast cancer that had spread to nearby lymph nodes—a group that is usually treated with chemotherapy to lower the risk of recurrence.
Genomic testing guided treatment decisions by assessing recurrence risk
Researchers used the Prosigna genomic test to analyze tumor gene activity and estimate the likelihood of cancer returning. Based on the results, patients with a score of 60 or below received only hormone therapy, while those with higher scores also received chemotherapy.
About 68% of participants were classified as low-risk. After five years, 93.6% of these patients who received only hormone therapy remained disease-free, compared with 94.8% of those who also had chemotherapy.
The difference—just over one percentage point—was below the study’s predefined threshold for clinical significance, suggesting chemotherapy may not provide meaningful additional benefit for this group. The analysis also found that only around 2% of low-risk patients were likely to gain substantial benefit from chemotherapy.
