Multi-parametric functional optical spectroscopy to monitor the metabolic and vascular changes in small head and neck tumors <i>in vivo</i> with radiation stress

We demonstrated a portable multi-parametric functional optical spectroscopy to monitor metabolic and vascular changes in small head and neck tumors <i>in vivo</i> with fractional radiation therapy. For the first time, we captured the key metabolic and vascular parameters of head and neck xenograft tumors <i>in vivo</i> prior to and post a total of 10 Gy fractional radiation therapy. Our animal studies showed dramatic vascular and metabolic changes in radioresistant head and neck tumors (rSCC-61) under radiation stress but not in radiosensitive head and neck tumors (SCC-61). Specifically, our data showed that rSCC-61 tumors had increased tissue oxygen saturation (indicating reoxygenation), increased total hemoglobin content (indicating blood perfusion), and increased oxygenated hemoglobin (indicating oxygen supply) post radiation therapy. Our study also showed that rSCC-61 tumors had decreased glucose uptake and increased mitochondrial function post-radiation therapy. In contrast, SCC-61 tumors had minimal changes in either vascular or metabolic parameters post-radiation treatment. These results demonstrated the potential of our portable multi-parametric functional optical spectroscopy to evaluate tumor vascular and metabolic changes under therapeutic stresses for future head and neck cancer research.