Radiotherapy induces an increase in serum antioxidant capacity reflecting tumor response

Area of Science:

• Oncology
• Radiation Oncology
• Cancer Biology

Background:

• Radiotherapy (RT) is a primary treatment for head and neck squamous cell carcinoma (HNSCC).
• Patient responses to RT vary, potentially due to antioxidant mechanisms counteracting RT-induced oxidative damage.
• Reactive oxygen species (ROS) generated by RT are crucial for its therapeutic effect.

Purpose of the Study:

• To investigate the relationship between local and systemic antioxidant responses to RT-induced ROS.
• To determine if these antioxidant responses correlate with treatment success in HNSCC.

Main Methods:

• Immunofluorescent staining for Nuclear factor erythroid 2-related factor 2 (NRF2) in cancer cells and patient tumor biopsies before and after RT.
• Analysis of total antioxidant capacity (TAC) in HNSCC cells *in vitro* and in patient serum during RT.

Main Results:

• NRF2 expression and TAC increased in HNSCC cells *in vitro* following RT.
• NRF2 expression also increased in patient tumors, correlating with elevated serum TAC during RT.
• Elevated serum TAC during RT was associated with diminished local tumor control.

Conclusions:

• RT induces NRF2 expression and upregulates TAC, potentially diminishing the efficacy of RT-induced ROS.
• Serum TAC levels during RT may serve as a predictive biomarker for treatment outcomes in HNSCC patients.