Cutting the number of radiation sessions by about 20% for prostate cancer patients who show signs of recurrence after surgery delivers cancer control comparable to standard treatment, a new study found. The approach is expected to offer a treatment option that eases the burden on patients who must return to the hospital repeatedly for weeks.
Asan Medical Center said the finding came from a randomized phase 3 clinical trial conducted by Professor Kim Young-seok and specialist Song Young-joo of its radiation oncology department, together with Professor Park Won of the radiation oncology department at Samsung Medical Center. The trial enrolled patients with biochemical recurrence after prostate cancer surgery. The results were published in the Journal of Clinical Oncology.
Biochemical recurrence refers to a state in which prostate-specific antigen (PSA) levels rise again above a certain threshold after a prostatectomy. Even when imaging tests detect no tumor, it suggests cancer cells may remain in the body. In such cases, radiation can be delivered to the area around the surgical site to suppress recurrence.
Standard treatment delivers 2 gray (Gy) of radiation per session. Hypofractionated treatment raises the dose per session while reducing the total number of sessions. It is already widely used for prostate cancer patients who receive radiation without surgery, but high-quality clinical evidence directly comparing it with standard treatment in patients with biochemical recurrence after surgery had been lacking.
The research team enrolled 316 patients who developed biochemical recurrence after radical prostatectomy between 2019 and 2021, randomly assigned them to two treatment groups and followed them for about five years. The hypofractionated group received 2.5 Gy per session in 26 sessions, for a total of 65 Gy. The standard group received 2 Gy per session in 33 sessions, for a total of 66 Gy. All patients were treated with intensity-modulated radiation therapy and image-guided radiation therapy, which uses daily CT scans to verify treatment positioning.
Four-year biochemical progression-free survival, the share of patients who survived without a renewed rise in PSA after treatment, was 80.1% in the hypofractionated group and 78.1% in the standard group. There was no statistically significant difference between the two groups. Four-year distant metastasis-free survival was also similar at 91.7% and 91.0%, respectively, and four-year prostate cancer-specific survival was 100% in both groups.
Moderate gastrointestinal side effects, including rectal bleeding, occurred in 7.6% of the hypofractionated group, higher than in the standard group. They mainly occurred in patients who did not use an endorectal balloon, and there were no severe side effects. All such side effects had resolved by the time of the final follow-up. There was no difference between the two groups in digestive and urinary symptoms or quality of life as assessed by patient questionnaires.
The research team said cutting the number of sessions from 33 to 26 could reduce the burden of hospital visits for patients and allow more efficient use of radiation therapy resources.
"Patients with biochemical recurrence after surgery carry a heavy burden, worrying about recurrence while having to visit the hospital repeatedly for weeks," Kim said. "This study confirmed that reducing the number of sessions can maintain cancer control and quality of life similar to existing treatment." He added, "Since some gastrointestinal side effects occurred more frequently, it is important to apply precise image-guided treatment together with methods to protect the rectum."