EXPERT Trial - EXamining PErsonalised Radiation Therapy for low-risk early breast cancer

This is a randomised phase III trial of adjuvant radiation therapy versus observation following breast conserving surgery and endocrine therapy in patients with molecularly characterised luminal A early breast cancer. The purpose of this study is to see whether a specialised laboratory test (Prosigna (PAM50) Assay) of breast cancer tissue can be used to choose women who can safely avoid radiation therapy because there is a low risk of the cancer coming back. New Zealand sites are Waikato Hospital, Christchurch Hospital, Wellington Hospital and Palmerston North Hospital.

The current standard of care for patients with early breast cancer is radiation therapy (RT) after breast conserving surgery, to improve local control and survival. However, breast cancer is a complex disease, and the absolute benefit of RT in individual patients varies substantially. This approach potentially may lead to overtreatment for a substantial proportion of patients and unnecessary treatment toxicity, financial costs and logistical challenges for patients. However, randomised trials have not consistently identified patients who may safely avoid RT using conventional clinical-pathologic characteristics.

EXPERT is an investigator-initiated trial which presents a unique opportunity to improve personalised use of radiation therapy in patients with early breast cancer according to their individual risks of local recurrence.

The primary aim of the trial is to see whether a genomic test of breast cancer tissue can be used to identify women who can safely avoid radiation therapy after breast cancer surgery. The need for radiation therapy after breast cancer surgery depends on the risk of the cancer reoccurring. If the risk is very small, there may be no need for radiation therapy. If a doctor could identify women who have a very small risk of the cancer coming back, these women may not need radiation therapy and could avoid its side effects.