Pulsed reduced dose rate radiotherapy: a narrative review

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Biology

Background:

• Pulsed reduced dose rate (PRDR) radiotherapy, also known as pulsed low dose rate (PLDR) radiotherapy, delivers radiation at lower dose rates in a pulsed manner.
• This method aims to increase tumor sensitivity while minimizing damage to normal tissues, making it a potential strategy for treating recurrent tumors.

Purpose of the Study:

• To review the biological rationale, clinical applications, and future prospects of PRDR radiotherapy across various cancer types.
• To consolidate current evidence on the efficacy and safety of PRDR in treating recurrent malignancies.

Main Methods:

• A comprehensive literature search was conducted using Medline, ClinicalTrials.gov, and Google Scholar.
• Keywords included "PRDR", "Pulsed reduced dose rate", "Pulsed low dose rate", and "PLDR" in combination with cancer types.
• All retrieved publications were reviewed, and key references were cross-checked for a balanced review.

Main Results:

• PRDR exhibits radiobiologic advantages such as reoxygenation, redistribution, and immune regulation, contributing to its efficacy and reduced toxicity.
• Feasibility demonstrated across intensity-modulated radiotherapy (IMRT) and pencil beam scanning (PBS) proton therapy for recurrent tumors.
• Clinical evidence supports PRDR efficacy in central nervous system (CNS) tumors, recurrent breast cancer, head and neck cancers, gastrointestinal cancers, and cervical cancers.

Conclusions:

• PRDR radiotherapy demonstrates promising efficacy and safety, particularly for re-irradiation of various malignancies.
• It is especially effective for CNS tumors with manageable toxicity and shows potential in recurrent breast, head and neck, and gastrointestinal cancers.
• PRDR is a viable option for re-irradiation, with potential for expanded use and new hope for challenging cancer diagnoses.