Biopsy results of new suspicious breast imaging findings in patients undergoing neoadjuvant chemotherapy for primary breast cancer

Purpose: We aimed to describe the outcomes (benign vs. malignant) of biopsies performed for new findings in breast cancer patients actively undergoing neoadjuvant chemotherapy (NAC). In patients whose primary breast tumor was responding to NAC on imaging, it was hypothesized that new suspicious findings on imaging were more likely to be benign findings on image-guided biopsy.

Methods/Materials: A retrospective chart review of all patients who underwent neoadjuvant chemotherapy for primary breast cancer at a large academic medical center from 2013-2021 was performed. Patients were excluded if biopsies were not image-guided, were taken from the original primary tumor, or were taken from a lesion present on initial extent of disease imaging. Patients were also excluded if initial imaging was performed at an outside facility.

Results: Eleven patients with suspicious findings on MRI, ultrasound, or mammography were included for analysis. Of the 11 patients, image-guided biopsy of the breast (n = 8, 72%) or an axillary lymph node (n = 3, 28%) was performed on average 113.5 days after the initiation of NAC. All biopsies were taken prior to surgical resection of the primary tumor. All 8 patients who underwent breast biopsies of either the ipsilateral breast as the primary tumor (n = 3, 36%) or the contralateral breast (n=5, 63%) had pathological findings that were determined to be benign. Similarly, all 3 patients who underwent biopsy of an ipsilateral (n=1) or contralateral axillary lymph node (n=2) were found to have benign biopsy results.

Conclusions: Based on the findings of our study, image-guided biopsy of new suspicious findings on imaging of patients whose primary breast tumor is responding to NAC may not be as useful as previously thought and may cause unwarranted psychological stress.