Thermoradiotherapy planning: Integration in routine clinical practice

Area of Science:

• Oncology
• Medical Physics
• Radiotherapy Research

Background:

• Combined radiotherapy and hyperthermia (HT) offer synergistic anti-cancer effects.
• Understanding these interactions is crucial for optimizing treatment planning.
• Current planning lacks integrated platforms for these combined modalities.

Purpose of the Study:

• Evaluate experimental data on combined radiotherapy and HT cytotoxicity.
• Assess requirements for integrating HT and radiotherapy planning into a single platform.
• Model the synergistic mechanisms of HT to improve treatment planning.

Main Methods:

• Review of experimental data on combined radiotherapy and HT cytotoxicity.
• Analysis of synergistic mechanisms: DNA repair inhibition, targeting hypoxic cells, and enhanced perfusion.
• Application of the linear-quadratic (LQ) model for radiosensitization.
• Evaluation of a linear-quadratic model-based thermoradiotherapy planning (TRTP) system.

Main Results:

• Hyperthermia mechanisms (DNA repair inhibition, hypoxic cell targeting, perfusion enhancement) have distinct dose-effect relationships and timing requirements.
• The LQ model can effectively model radiosensitization due to DNA repair inhibition.
• A TRTP system demonstrated hyperthermia's potential for dose escalation (e.g., ~10 Gy in prostate cancer).

Conclusions:

• Thermoradiotherapy planning (TRTP) is feasible and essential for optimal clinical application of combined HT and radiotherapy.
• Further data on LQ parameters for various tissues and temperatures are needed for reliable TRTP.
• Modeling hyperthermia's effects on hypoxic cells, including reoxygenation, is the next critical step.