Cutting treatment sessions from 33 to 26 yields equivalent outcomes, offering potential savings of over 5 billion won in national health insurance costs; findings published in Journal of Clinical Oncology
Asan Medical Center's Professor Kim Young-seok leads phase 3 trial on post-surgical patients with rising PSA levels
Prostate cancer is the most common cancer among men in South Korea, and even after surgical removal of the prostate, one in three or four patients experiences a "biochemical recurrence" — a renewed rise in prostate-specific antigen (PSA) levels — within 10 years. A new study has found that hypofractionated radiation therapy, which reduces the number of treatment sessions by about 20 percent, achieves cancer control comparable to the conventional approach.
A research team led by Professor Kim Young-seok and specialist Song Young-ju of the Department of Radiation Oncology at Asan Medical Center, along with Professor Park Won of the Department of Radiation Oncology at Samsung Medical Center, compared treatment outcomes by number of sessions in prostate cancer patients who experienced biochemical recurrence after surgery. The results showed that reducing sessions from 33 to 26 produced similar cancer control.
The findings from this randomized phase 3 clinical trial were recently published in the Journal of Clinical Oncology (impact factor: 44.7), one of the world's leading oncology journals.
Biochemical recurrence refers to a renewed rise in PSA levels above a certain threshold following prostatectomy. Even when imaging does not reveal a distinct tumor, the condition signals a possibility that cancer cells remain. Left untreated, it frequently progresses to sustained PSA elevation and detectable recurrence on imaging. Radiation therapy targeting the area around the surgical site is the only curative treatment option in such cases.
Conventional radiation therapy delivers 2 gray (Gy) — a unit of radiation dose — per session, while hypofractionated radiation therapy raises the per-session dose to 2.5 Gy, reducing the total number of sessions required.
Hypofractionated radiation therapy is already widely used for prostate cancer patients seeking a cure through radiation alone, without surgery. However, high-level clinical evidence directly comparing it with the standard treatment in patients with post-surgical biochemical recurrence had been lacking.
From 2019 to 2021, Professor Kim's team enrolled 316 prostate cancer patients who had developed biochemical recurrence after radical prostatectomy. The patients were randomly assigned to either a hypofractionated radiation therapy group or a conventional standard radiation therapy group and followed for approximately five years.
All patients received intensity-modulated radiation therapy, which precisely concentrates radiation on the tumor site, as well as image-guided radiation therapy, which uses daily CT scans to verify treatment positioning. The hypofractionated group received 2.5 Gy per session for a total of 65 Gy over 26 sessions, while the conventional group received 2 Gy per session for a total of 66 Gy over 33 sessions.
The primary endpoint — the four-year biochemical progression-free survival rate, meaning the proportion of patients who survived without a renewed PSA rise after treatment — was 80.1 percent in the hypofractionated group and 78.1 percent in the conventional group, a difference that was not statistically significant.
The four-year distant metastasis-free survival rate, reflecting the proportion of patients who survived without cancer spreading beyond the irradiated area to other organs, was 91.7 percent in the hypofractionated group and 91.0 percent in the conventional group. The four-year prostate cancer-specific survival rate — the proportion of patients who did not die from prostate cancer — was 100 percent in both groups.
Moderate gastrointestinal side effects, including rectal bleeding, were temporarily higher in the hypofractionated group at 7.6 percent compared with the conventional group. No severe side effects were observed, and the reactions occurred mainly in patients who did not use an intrarectal balloon. All side effects had resolved by the final follow-up. Patient-reported quality of life, covering gastrointestinal and urinary function among other measures, also showed no significant difference between the two groups.
Given that the main treatment outcomes and side effects were similar between the two groups, the researchers said reducing sessions from 33 to 26 could serve as a new treatment option that lowers the burden of hospital visits for patients while allowing more efficient use of radiation therapy resources. With more than 8,000 radical prostatectomies performed annually in South Korea, wider adoption of hypofractionated radiation therapy is expected to contribute savings of at least 5 billion won ($3.74 million) per year in national health insurance costs.
"Patients with biochemical recurrence after prostate cancer surgery face not only the anxiety of cancer returning but also the significant burden of repeated hospital visits over several weeks for radiation therapy," said Kim Young-seok, the corresponding author and a professor in the Department of Radiation Oncology at Asan Medical Center. "This study confirmed that reducing the number of sessions can maintain cancer control and quality of life comparable to conventional treatment." He added that, given the somewhat higher rate of gastrointestinal side effects observed with hypofractionated therapy, "it is important to combine precise image-guided radiation therapy with measures to protect the rectum."
kty@heraldcorp.com
