In this retrospective study, we evaluated imaging data from 65 breast cancer patients that were obtained one to three days before the initiation of neoadjuvant chemotherapy (NAC). Imaging was performed with a dynamic optical tomography breast imaging system (DOTBIS) over the course of a breath hold. From this imaging data, we extracted time-dependent signal traces of the total hemoglobin in the whole volume of the tumor-bearing breast. The inflection point and the slope at the steepest part of the curve were calculated for both the ascending (patient holds her breath) and descending slopes (patient releases her breath and starts breathing normally again). Our results show statistically significant differences in vascular changes between patients with a pathologic complete response (pCR) and non-pCR patients. This suggests that differences in the tumor-bearing breasts of these two patient groups exist even before treatment is started.