Correlation of tissue oxygenation and skin toxicity to determine the effectiveness of photon vs proton therapy in breast cancer subjects

The American Cancer Society has estimated that a total of 1.8 million new cancer cases will arise in 2020, 15% percent of which are breast cancer. Radiation therapy (RT) is widely used post mastectomy or lumpectomy as a method of avoiding recurrence of disease in affected regions. Photon and proton therapy are among the main forms of RT currently applied to breast cancer patients. The effectiveness of photon vs proton therapy has been studied in various cancer models from differences in subjective clinical grading of radiation dermatitis (RD), a common side effect of RT. Herein, an objective physiological imaging approach using near-infrared optical techniques is implemented to quantitatively differentiate the effectiveness of proton vs photon therapy in breast cancer subjects undergoing RT. A 6-8 week longitudinal pilot study (WIRB approved) was carried out on 10 breast cancer subjects undergoing RT at Miami Cancer Institute (MCI). The chest wall, axilla, and lower neck were imaged on the irradiated and the non-irradiated (contralateral) sides of the torso to measure for tissue oxygenation changes. From preliminary analysis, it was observed that were distinct differences in tissue oxygenation and RD in the irradiated regions when compared to their contralateral nonirradiated tissue (reference). Changes in tissue oxygenation and skin toxicity (i.e. RD clinical grading) were more localized and less severe in subjects receiving proton therapy compared to photon therapy. Quantitative comparison of oxygenation changes and its correlation to the skin toxicity levels in photon vs proton therapy treated breast cancer subjects is currently carried out.