The following article features coverage from the 2019 San Antonio Breast Cancer Symposium. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

The addition of image-guided core-needle biopsy to trimodality imaging was not predictive of pathologic complete response (pCR) after surgery for patients with breast cancer according to the primary analysis of the phase 2 NRG-BR005 trial (ClinicalTrials.gov Identifier: NCT03188393). The trial results were presented at the 2019 San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Texas.

The trial sought to evaluate the accuracy of image-directed tumor bed biopsy with trimodality imaging in predicting pCR after surgery in patients who achieve a clinical and radiological complete or near-complete response after neoadjuvant therapy. The researchers defined pCR as the resolution of both invasive disease and ductal carcinoma in situ (DCIS).

The authors hypothesized that the addition of image-directed tumor bed biopsy to trimodality imaging could help identify patients who could forgo breast-conserving surgery and be treated only with radiation instead. 

The trial enrolled patients with stage I-IIIA invasive ductal carcinoma and operable disease (ie, T1-T3). Eligible patients were those who, after neoadjuvant therapy, achieved a clinical complete response and radiological complete or near-complete response by trimodality imaging.


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Among the 98 evaluable patients, 36 had a non-pCR after surgery, of which 18 were successfully predicted by tumor bed biopsy in addition to trimodality imaging, yielding a negative predictive value 77.5% (95% CI, 66.6-86.1), which was below the desired threshold of 90%. The sensitivity was 50.0% (95% CI, 32.9-67.1).

A subgroup analysis revealed that for patients with HER2-positive disease, the negative predictive value nearly reached the 90% threshold at 89.5% (95% CI, 75.2-97.1). The sensitivity was 60.0% (95% CI, 26.2-87.8).

The study presenter Mark Basik, MD, of Jewish General Hospital in Montréal, QC, Canada, explained that if DCIS patients were excluded and pCR was defined as only invasive disease, then the negative predictive value of the entire group reached 89% and the sensitivity was 61%.

“At this point in time, these findings do not support breast conserving treatment without surgery based on the study criteria of complete clinical response and radiological near or complete radiological response and negative tumor bed biopsies,” concluded Dr Basik.

Read more of Cancer Therapy Advisor‘s coverage of SABCS by visiting the conference page.

Reference

  1. Basik M, Cecchini RS, De Los Santos JF, et al. Primary analysis of NRG-BR005, a phase II trial assessing accuracy of tumor bed biopsies in predicting pathologic complete response (pCR) in patients with clinical/radiological complete response after neoadjuvant chemotherapy (NCT) to explore the feasibility of breast-conserving treatment without surgery. Oral presentation at: 2019 San Antonio Breast Cancer Symposium; December 10-14, 2019; San Antonio, TX. Abstract GS5-05.