Potential Therapeutic Improvements in Prostate Cancer Treatment Using Pencil Beam Scanning Proton Therapy with LETd Optimization and Disease-Specific RBE Models

• Published in: Cancers Vol. 16; no. 4; p. 780
• Main Authors: Vieceli, Michael, Park, Jiyeon, Hsi, Wen Chien, Saki, Mo, Mendenhall, Nancy P., Johnson, Perry, Artz, Mark
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.02.2024
• Subjects: Cancer therapies; Clinical outcomes; disease-specific/prostate-cancer-specific LET-dependent RBE modeling; Dosimetry; LET-optimized pencil beam scanning proton therapy; Optimization; Patients; Prostate cancer; prostate cancer treatment; Protons; Radiation therapy; Risk groups; Scanning; Statistical analysis; Toxicity; X-rays
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers16040780

Purpose: To demonstrate the feasibility of improving prostate cancer patient outcomes with PBS proton LETd optimization. Methods: SFO, IPT-SIB, and LET-optimized plans were created for 12 patients, and generalized-tissue and disease-specific LET-dependent RBE models were applied. The mean LETd in several structures was determined and used to calculate mean RBEs. LETd- and dose–volume histograms (LVHs/DVHs) are shown. TODRs were defined based on clinical dose goals and compared between plans. The impact of robust perturbations on LETd, TODRs, and DVH spread was evaluated. Results: LETd optimization achieved statistically significant increased target volume LETd of ~4 keV/µm compared to SFO and IPT-SIB LETd of ~2 keV/µm while mitigating OAR LETd increases. A disease-specific RBE model predicted target volume RBEs > 1.5 for LET-optimized plans, up to 18% higher than for SFO plans. LET-optimized target LVHs/DVHs showed a large increase not present in OARs. All RBE models showed a statistically significant increase in TODRs from SFO to IPT-SIB to LET-optimized plans. RBE = 1.1 does not accurately represent TODRs when using LETd optimization. Robust evaluations demonstrated a trade-off between increased mean target LETd and decreased DVH spread. Conclusion: The demonstration of improved TODRs provided via LETd optimization shows potential for improved patient outcomes.