Imaging Technique Detects Breast Tumor Responses to Chemotherapy
A prospective multicenter trial suggests that diffusion-weighted MRI is a reliable biomarker in a subset of women with breast cancer.
Diffusion-weighted MRI holds strong potential to reveal early changes in tumors responding to therapy, but past studies on its usefulness have provided conflicting results. This underscores the need for well-designed, large-scale multicenter clinical trials.
In a study published Sept. 4 in the journal Radiology, researchers conducted a prospective multicenter study to evaluate the effectiveness of diffusion-weighted MRI for assessing breast cancer response to chemotherapy. The researchers enrolled 272 women with breast cancer at 10 institutions. Each woman underwent breast diffusion-weighted MRI before chemotherapy treatment, at early treatment (three weeks), at midtreatment (12 weeks), and after treatment.
In the final analysis of 242 patients, changes detected by diffusion-weighted MRI at 12 weeks and after treatment predicted pathologic complete response -- the lack of all signs of cancer in tissue samples removed during surgery or biopsy after treatment with chemotherapy. However, the midtreatment result was only significant for the tumor subset that was positive for a cell protein called hormone receptor (HR) but negative for human epidermal growth factor receptor 2 (HER2), a protein involved in cell growth. A model that took into account both tumor subtype and diffusion-weighted MRI midtreatment results improved predictive performance compared to the diffusion-weighted MRI findings alone.
According to the authors, this is the first prospective multicenter clinical trial to validate diffusion-weighted MRI as a reliable biomarker of breast cancer response to therapy. The findings suggest that this technique may enable objective assessment of therapeutic efficacy, particularly for patients with HR-positive, HER2-negative tumors. This may have special clinical importance, as HR+/HER2- tumors are less likely to shrink in response to chemotherapy and less often achieve pathologic complete response.