Could an Emerging NacBI-RADS System for mpMRI Bolster Assessment of NAC Response?

New research suggests that a variation of the BI-RADS system specific to multiparametric MRI (mpMRI) assessment of neoadjuvant chemotherapy (NAC) response may provide a viable alternative to the RECIST 1.1 criteria.

For the retrospective study, recently published in European Radiology, researchers evaluated the utility of a neoadjuvant breast imaging reporting and data system (NacBI-RADS) in 68 patients (mean age of 51.8) with breast cancer who had staging and post-NAC MRIs. According to the study, the NacBI-RADS system utilizes four key parameters including peritumoral edema, post-contrast tumor size, change in apparent diffusion coefficient (ADC) and lymph node status (Node-RADS). The study authors noted that 63 percent of the cohort had residual disease and 37 percent achieved a pathological complete response (pCR).

Is the NacBI-RADS System Better Than the RECIST 1.1 Criteria for Assessing Response to Neoadjuvant Chemotherapy?

In comparison to the RECIST 1.1 criteria, the study authors found that the NacBI-RADS system offered averages of 8 percent higher sensitivity (86.7 percent vs. 78.7 percent) and 26.7 percent higher specificity (100 percent vs. 73.3 percent) across three radiologists with varied experience in breast imaging.

Researchers also noted over a 36 percent higher average positive predictive value (PPV) (100 percent vs. 63.7 percent) and a seven percent higher average negative predictive value (NPV) (92.7 percent vs. 85.7 percent) with the NacBI-RADS system.

“ … The composite NacBI-RADS score showed robust ability to discriminate between patients with residual disease and those achieving pCR, with very high inter-reader reproducibility among radiologists with different experience levels. In addition, when compared with conventional methods traditionally used to assess NAC response based on size criteria, NacBI-RADS demonstrated higher sensitivity and diagnostic accuracy,” noted lead study author Federica Cicciarelli, MD, who is affiliated with the Department of Radiological, Oncological and Pathological Sciences at the University of Rome in Italy, and colleagues.

How the NacBI-RADS System Could Impact Surgical Planning and Post-Op Monitoring

The study authors suggested that theNacBI-RADS scoring system could have a significant impact on surgical planning decisions — such as resection extent and choosing between mastectomy and breast-conserving surgery — as well as post-op monitoring.

“In clinical practice, a structured system such as NacBI-RADS could provide radiologists with a standardized framework for reporting post-NAC MRI examinations, facilitating multidisciplinary discussion and supporting surgical decision-making in patients who may be candidates for treatment de-escalation,” emphasized Cicciarelli and colleagues.

(Editor’s note: For related content, see “Post-NAC Contrast-Enhanced Mammography: Is Delayed Image Acquisition the Best Way to Assess for Residual Disease?,” “MRI Study Reveals Potentially Severe Impact of NAC Upon Heart and Brain Function in Breast Cancer Patients” and “Study: MRI May Help Predict Outcomes in Treatment for Triple-Negative Breast Cancer.”)

Beyond the inherent limitations of a single-center retrospective study, the authors acknowledged that variations with b-values, readout techniques and ROI placement can impact assessment of ADC changes. The researchers emphasized that multicenter prospective studies are necessary prior to broader utilization of NacBI-RADS.