Results from NRG Oncology's BR005 study show that breast-conserving treatment without surgery cannot be recommended, based on the study criteria of clinical complete response, radiological complete response (rCR)/near rCR, and negative tumour bed biopsies.

These findings were presented at the 2019 San Antonio Breast Cancer Symposium, held December 10-14.

This phase II study, which opened in June 2017, was designed as a two-stage trial to assess the accuracy of tumour bed biopsies in predicting pathologic response in patients with clinical complete and radiological complete/near complete response after neoadjuvant chemotherapy to determine if they could avoid surgery.

All patients had received chemotherapy for their breast cancer, but had not yet had surgery.

All underwent an image-guided biopsy after receiving chemotherapy.

A total of 105 patients were enrolled from August 2017 through June 2019, with 98 being evaluable for analysis.

Accrual was temporarily closed for futility analysis on June 26, 2019, because 36 of the evaluable patients had residual disease at surgery, which actually met the numbers for the primary analysis.

The negative predictive value of the biopsy was 77.5% (95%CI: 66.8% to 86.1%) which did not meet the pre-specified threshold of >90% required to support the feasibility of initiating a study in which surgery could be omitted.

"Further analysis including central review of tri-modality imaging and assessment of an imaging algorithm with and without the addition of biopsy are underway. Once these are combined with information on biologic subtypes, a new prediction model will be defined," according to Mark Basik, MD, from Jewish General Hospital, and lead investigator of the study.

Source: NRG Oncology