Near-Infrared Diffuse Optical Imaging for Early Prediction of Breast Cancer Response to Neoadjuvant Chemotherapy: A Comparative Study Using 18F-FDG PET/CT

Diffuse optical spectroscopic imaging (DOSI) is used as an indicator of tumor blood volume quantified by tissue hemoglobin concentrations. We aimed to determine whether early changes in tumor total hemoglobin (tHb) concentration can predict a pathologic complete response (pCR) to neoadjuvant chemotherapy in patients with operable breast cancer, and we compared the predictive value of pCR between DOSI and F-18-FDG PET combined with CT. Methods: Of the 100 patients enrolled, 84 patients were prospectively evaluated for primary objective analysis. Sixty-four of the patients underwent both sequential DOSI scans at baseline after their first and second chemotherapy courses and F-18-FDG PET/CT at baseline and after their second chemotherapy course. The mean tHb (tHb(mean)) concentration and SUVmax of the lesion were measured using DOSI and F-18-FDG PET/CT, respectively, and the percentage change in tHbmean (Delta tHb(mean)) and change in SUVmax (Delta SUVmax) were calculated. We compared the diagnostic performances of DOSI and F-18-FDG PET/CT for predicting pCR via the analysis of the receiver-operating-characteristic curves. Results: pCR was achieved in 16 patients, and neoadjuvant chemotherapy caused a significant reduction of Delta tHb(mean) in pCR compared with non-pCR after the 2 chemotherapy courses. When the tentative Delta tHb(mean) cutoff values after the first and second courses were used, the ability to predict pCR was as follows: 81.2% sensitivity/47.0% specificity and 93.7% sensitivity/47.7% specificity, respectively. Comparison of the diagnostic performances of DOSI and F-18-FDG PET/CT revealed areas under the curve of 0.69 and 0.75 of Delta tHb(mean) after the first and second courses, respectively, which were lower than those of Delta SUVmax (0.90). Conclusion: DOSI predicted pCR in patients with breast cancer with moderate accuracy. The diagnostic performance of DOSI was inferior to that of the early metabolic response as monitored by F-18-FDG PET/CT.