Early identification of non-responding locally advanced breast tumors receiving neoadjuvant chemotherapy

Diffuse optical spectroscopy (DOS) may be advantageous for monitoring tumor response during chemotherapy treatment, particularly in the early treatment stages. In this paper we perform a second analysis on the data of a clinical trial with 25 breast cancer patients that received neoadjuvant chemotherapy. Patients were monitored using delayed contrast enhanced MRI and additionally with diffuse optical spectroscopy at baseline, after 1 cycle of chemotherapy, halfway therapy and before surgery. In this analysis hemoglobin content between tumor tissue and healthy tissue of the same breast is compared on all four monitoring time points. Furthermore, the predictive power of the tumor-healthy tissue difference of HbO 2 for non-responder prediction is assessed. The difference in HbO 2 content between tumor and healthy tissue was statistically significantly higher in responding tumors than in non-responding tumors at baseline (10.88 vs -0.57 μM, P=0.014) and after one cycle of chemotherapy (6.45 vs -1.31 μM, P=0.048). Before surgery this difference had diminished. In the data of this study, classification on the HbO 2 difference between tumor and healthy tissue was able to predict tumor (non-)response at baseline and after 1 cycle with an area-under-curve of 0.95 and 0.88, respectively. While this result suggests that tumor response can be predicted before chemotherapy onset, one should be very careful with interpreting these results. A larger patient population is needed to confirm this finding.