Risk-optimized proton therapy to minimize radiogenic second cancers.

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Research

Background:

• Proton therapy offers lower second cancer risks than photon therapy.
• Previous proton therapy planning lacked algorithmic optimization for minimizing secondary cancer risks.
• Prostate cancer treatment necessitates minimizing risks to adjacent organs like the bladder and rectum.

Purpose of the Study:

• To establish the feasibility of risk-optimized proton therapy.
• To identify optimal beam angles and fluence weights for minimizing second cancer risk in the bladder and rectum for prostate cancer patients.
• To compare risk reduction strategies using established cancer risk models.

Main Methods:

• Utilized six distinct risk models to predict excess relative risk of second cancer.
• Integrated a commercial treatment planning system with a proprietary risk-optimization algorithm.
• Incorporated normal-tissue dose constraints into the treatment planning process.

Main Results:

• Risk-optimized proton therapy demonstrated feasibility in reducing secondary cancer risks.
• A specific risk model incorporating fractionation, initiation, inactivation, repopulation, and promotion selected anterior and lateral beams.
• This optimized beam arrangement reduced relative risk by 21% for the bladder and 30% for the rectum compared to lateral-opposed beams.
• Varied results were observed across different risk models.

Conclusions:

• Risk-optimized proton therapy is feasible and can significantly reduce second cancer risks.
• Algorithmic optimization of beam angles and fluence is a promising strategy for enhancing proton therapy safety.
• Further research across multiple risk models is warranted to refine optimal treatment planning for minimizing long-term cancer risks.