Tumor vascular reactivity as a marker to predict tumor response to chemotherapy

Breast cancer is one of the most common cancers for females. To monitor chemotherapeutic efficacy of breast cancer, medical imaging systems such as X-ray mammography, computed tomography, magnetic resonance imaging, and ultrasonography have been used. Currently, it can take up to 3 to 6 weeks to see the tumor response from chemotherapy by monitoring tumor volume changes. In this study, we used near infrared spectroscopy to see if we can predict breast cancer treatment efficacy earlier than tumor volume changes by monitoring tumor vascular reactivity during inhalational gas interventions. The results show the amplitude of oxy-hemoglobin changes (vascular reactivity) during hyperoxic gas inhalation is well correlated with tumor growth, and responded 1 day earlier than tumor volume changes after chemotherapy. In addition, we fitted oxyhemoglobin concentration increase during hyperoxic gas intervention using a double exponential fitting model. From these, we found the change of amplitude 1 value is well matched with tumor growth and regression. Especially, it predicts the chemotherapeutic response of breast tumor better than the amplitude of oxyhemoglobin concentration change during hyperoxic gas intervention. These results may imply that near infrared spectroscopy with respiratory challenges can be useful in early detection of tumor and also in prediction of tumor response to chemotherapy.