EndoPredict – can this prognostic test predict treatment success in breast cancer?

This study investigated if a prognostic tool called EndoPredict can predict the success of treatment in hormone receptor-positive breast cancer (BC). They found that high scores using EndoPredict predicted treatment benefit in patients with BC. 

Breast cancer (BC) is one of the most common cancers. BC treatment can involve chemotherapy (CT) or endocrine therapy (ET). Some BC tumors are called estrogen receptor-positive (ER+). These respond to the estrogen hormone to grow. Patients with ER+ BC are treated with ET. Adjuvant treatment (AT) is the term used for treatment after BC tumor removal. AT may last up to 5 years for some patients. The aim of AT is to reduce the risk of recurrence. 

It is difficult to predict if a patient will benefit from ET. Prognostic tools like EndoPredict can be used to estimate clinical benefit. EndoPredict takes a sample of the BC tumor and measures gene expression. If certain genes are expressed then it suggests there is a higher risk of BC recurrence. It is unclear if EndoPredict accurately predicts clinical benefit and recurrence risk in patients with ER+ BC.

This study included 3746 women with ER+ BC. These patients received 5 years of ET. Some women also had CT. The authors took BC tumor samples before ET began. These samples were used by EndoPredict to identify genes. This produces and EndoPredict score. The higher the score the greater the risk of recurrence. 

The 10-year disease recurrence (DR) risk was 20% higher in women treated with ET than ET + CT patients. EndoPredict accurately predicted DR in both ET and ET + CT-treated patients. Increasing EndoPredict scores were associated with a higher risk of BC recurrence in women treated with ET or ET + CT.

EndoPredict scores accurately predicted the time without BC. EndoPredict scores of 5 or higher were associated with a 57% higher risk of BC recurrence in ET-only patients. This compared to a 29% increased risk for women treated with ET + CT.

The authors concluded that high scores using EndoPredict predicted chemotherapy benefit in patients with ER+ BC.

This study looked back in time to analyze data from different clinical trials. The treatment protocols varied and this could also have an impact on the results.