Diffusion-Weighted Imaging Detects Early Physiologic Change of Tumor Following Tamoxifen Treatment in an MNU-Induced Breast-Cancer Rat Model

Guihua Zhai¹, Clinton Grubbs¹, Cecil Stockard¹, Heidi Umphrey¹, Timothy Beasley¹, Hyunki Kim¹

Tamoxifen is a clinically approved hormonal therapeutic agent for ER+ breast cancer in both neoadjuvant and adjuvant settings. However, a wide range of tamoxifen sensitivity has been observed among patients, and therefore it would be necessary to select patients favorably responding to tamoxifen ideally based on non-invasive imaging techniques. Diffusion-weighted imaging (DWI) was employed to assess the early tumor response following tamoxifen therapy in a methylnitrosourea (MNU)-induced breast-cancer rat model. Also, significant correlation between ER-beta density and early ADC change was verified, suggesting ER-beta as a prognostic biomarker for effective tamoxifen therapy as well.