Posted: Tuesday, August 8, 2023
Stephane Supiot, MD, PhD, of the University of Nantes, France, and colleagues demonstrated the dosimetric feasibility of a novel approach to radiotherapy for patients with prostate cancer. The investigators focused on implementing tumoral and hypoxia-guided dose escalation using a state-of-the-art ring gantry radiotherapy system. The findings, presented at the 2023 American Society of Clinical Oncology (ASCO) Breakthrough meeting (Abstract 73) in Yokohama, Japan, suggest the novel strategy may potentially enhance tumor control and reduce the risk of cancer recurrence without compromising the safety of surrounding organs.
In this study, three patients with intermediate-risk prostate cancer were selected and underwent external-beam radiation therapy as part of the PAIR prostate study. The researchers used pretherapeutic F-MISO (fluoromisonidazole) PET scans to identify both the gross tumor volume and the hypoxic region (biological tumor volume) within the prostate. The planning was based on three different treatment prescriptions to explore the potential of this innovative approach.
The first treatment regimen, standard fractionation, involved delivering 77 Gy/35 fractions to the planning target volume, with additional boosts of 95 Gy and 118 Gy in 35 fractions to the gross tumor volume and the hypoxic region, respectively. The second regimen, moderate hypofractionation, delivered 60 Gy/20 fractions with boosts of 67 Gy and 91 Gy in 20 fractions to the gross tumor volume and biological tumor volume, respectively. Finally, the high hypofractionation technique delivered 40 Gy/5 fractions with a gross tumor volume boost of 50 Gy in 5 fractions and as high a boost as possible to the hypoxic region using stereotactic body radiation therapy.
For the standard fractionation approach, the average radiation doses to the planning target volume, gross tumor volume, and biological tumor volume were well within acceptable ranges. The moderate and high hypofractionation techniques also demonstrated effective dose escalation to the targeted areas while keeping the doses within acceptable limits for the organs at risk, such as the bladder, rectum, and femoral heads, the investigators reported.
Disclosure: For full disclosures of study authors, visit coi.asco.org.