Purpose: Our goal was to determine the correlations between dynamic contrast-enhanced MRI (DCE-MRI) kinetics of breast cancers and axillary nodal status (ANS) which may have prognostic value in designing radiation therapy recommendations.
Methods and materials: A retrospective review identified 167 consecutive patients treated with external beam radiotherapy for invasive breast cancer from Jan 1, 2006 to Nov 1, 2007. Patients with DCE-MRI kinetic data from our institution who underwent axillary surgical staging prior to chemotherapy were included. ANS was assessed as positive or negative by pathology record review. For each primary cancer, maximum tumor diameter and kinetic values for initial peak enhancement (PE), percent initial rapid enhancement (RE), and percent delayed washout enhancement (WE) were measured with a computer-aided evaluation program. Univariate, multivariate, and receiver operating characteristic curve analyses were performed according to the ANS.
Results: Forty-six patients met study criteria, with 32 (70%) node-negative and 14 (30%) node-positive patients. Median PE was significantly greater in node-positive patients (209%) than in node-negative patients (138%, p = 0.0027). Similarly, median RE was significantly greater in node-positive patients (57%) than in node-negative patients (27%, p = 0.0436). WE was not different between groups (p = 0.9524). Median maximum tumor diameter was greater in node-positive patients (26 mm) than in node-negative patients (15 mm, p = 0.015). Multivariate analysis showed that only PE trended toward significance (p = 0.18).
Conclusions: DCE-MRI kinetics of primary breast cancers correlate with ANS. Multivariate analysis demonstrates the correlation is not due simply to underlying lesion size. If validated prospectively, DCE-MRI kinetics may aid as a tool in selecting patients or designing fields for radiation therapy.