Dose-Escalated Radiotherapy Safe, Effective for Patients With Prostate Cancer

A phase 3 study led by Christophe Hennequin, MD, PhD, and presented at the 2024 American Society of Clinical Oncology Genitourinary Cancers Symposium sought to determine the safety and efficacy of dose-escalated radiotherapy in combination with androgen deprivation therapy (ADT) in patients with high-risk prostate cancer.

Researchers noted that while a radiotherapy dose of 80 Gy is often well tolerated in patients, the dosage leads to an increased number of grade 3-4 toxicities when compared with a 70-Gy dosage.

Dr. Hennequin and colleagues randomly assigned 505 patients to receive either dose-escalated radiotherapy (80 Gy) with 3 years of ADT or a conventional dose (70 Gy) with 3 years of ADT.

The study’s primary end point was biochemical or clinical progression-free survival (bcPFS) at 5 years. Secondary end points included overall survival (OS), acute and late toxicity, and quality of life.

The dose-escalated radiotherapy group experienced an improved bcPFS when compared with the conventional radiotherapy group (hazard ratio [HR], 0.56; 95% CI, 0.40-0.76; P=.0005). The 5-year bcPFS was 91.4% and 88.1% in the dose-escalated radiotherapy group and the conventional radiotherapy group, respectively, and the 7-year bcPFS was 88.1% and 79.2%, respectively.

Researchers noted significant differences in prostate cancer-specific survival (HR, 0.48; 95% CI, 0.27-0.83; P=.0090) and OS (HR, 0.61; 95% CI, 0.44-0.85; P=.0039).

There were no significant differences between the 2 arms for late toxicities. In the dose-escalated radiotherapy group, 78.2% of patients experienced grade 2 or higher late toxicities, while 76.1% of patients in the conventional radiotherapy group reported the same.

“Dose-escalation radiotherapy in combination with long-term ADT is effective and safe, increasing not only the bcPFS rate but also specific survival and overall survival in high-risk prostate cancer patients without increasing long-term toxicity,” the researchers wrote.