New suspicious findings on breast MRI performed during therapy are unlikely to be cancer

Suspicious lesions on breast MRI exams performed following neoadjuvant therapy are relatively rare and unlikely to be cancerous, according to a new retrospective study.

Currently, there are no guidelines for managing these suspicious imaging findings spotted on exams performed over the course of breast cancer treatment, researchers explained in the American Journal of Roentgenology. After analyzing more than 400 MRIs, researchers found unusual lesions in 5.5% of cases.

None of these new suspected abnormalities turned out to be malignant, Donna A. Eckstein, MD, and colleagues with the department of radiology and biomedical imaging at the University of California, San Francisco, explained.

“Our findings suggest that new lesions that arise in the setting of neoadjuvant therapy are highly unlikely to represent a new site of malignancy, particularly if the index malignancy shows treatment response," the team wrote in the Jan. 13 study.

For their research, Eckstein et al. gathered 419 breast MRIs from 297 women, performed to assess their response to neoadjuvant treatment between 2010 and 2018. New lesions were assessed as BI-RADS 4 or 5 and pathologic testing determined if a finding was malignant.

After excluding some cases, the final group included 23 exams with suspicious findings that were separate from the area of known cancer. And of those cases, 13 were contralateral to the known malignancy, nine were ipsilateral and one involved the bilateral breasts.

The group maintained that further research performed in larger populations and different facilities will be needed to determine if clinicians can avoid biopsies for some of these patients going forward.

"Results in this small cohort suggest that these new findings are highly likely to be benign, particularly in the setting of response to therapy, which may potentially obviate biopsies in these patients in the future," the authors concluded.

Read the entire study in AJR here.