Hypofractionated radiation therapy as the “acceptable standard of practice” after prostatectomy



October 26, 2021

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Buyyounouski MK et al. Summary 3. Presented at ASTRO Annual Meeting; 24.-27. October 2021; Chicago.

Disclosure: Buyyounouski reports a research fellowship from Varian and honoraria from Elsevier and Wolters Kluwer. Please refer to the executive summary for all relevant financial information from the other researchers.

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According to study results, men who underwent hypofractionated radiation therapy after prostatectomy achieved comparable results in terms of safety and quality of life as men who received a conventional regimen.

Men assigned the hypofractionated regimen reported more gastrointestinal toxicity after completing radiation therapy.

Key Findings from the Phase 3 Study NRG Oncology GU003.

However, the hypofractionated regimen did not appear to be inferior to conventional radiation therapy in terms of patient-reported gastrointestinal and genitourinary toxicity at 2 years, as shown in results from the Phase 3 NRG Oncology GU003 study presented at the American Society for Radiation Oncology’s annual meeting was showing.

A longer follow-up period is necessary to assess disease control endpoints.

“Hypoffractionated post-prostatectomy radiation therapy is a new acceptable standard of practice [for this patient population]” Markus K. Buyyounouski, MD, Professor of Radiation Oncology and Director of Genitourinary Cancer in the School of Medicine at Stanford University said during the presentation.

About 98% of men diagnosed with prostate cancer live at least a decade after treatment, according to the study background. Therefore, long-term side effects and strategies to ensure quality of life are crucial.

Hypofractionated radiation therapy – which consists of fewer radiation fractions but higher doses per fraction – is “an accepted standard of practice” for men who will not have a prostatectomy, Buyyounouski said.

The NRG Oncology GU003 study – conducted at more than 90 centers in North America – was the first to investigate whether hypofractionated post-prostatectomy might be a viable option for men who had a prostatectomy and radiation therapy due to rising PSA levels needed, which suggested that her cancer had returned.

Buyyounouski and colleagues wanted to determine whether hypofractionated radiation therapy after prostatectomy – administered over 5 weeks – resulted in increased patient-reported urogenital or gastrointestinal toxicity compared to conventionally fractionated postoperative radiation therapy over 7 weeks.

“Maintaining quality of life was a major priority when testing the shorter course of treatment,” Buyyounouski said in a press release. “It is important for patients to know that accepting more convenient treatment does not mean that they have to compromise on quality of life.”

The study carried out between July 2017 and July 2018 included 296 men who met one of two criteria: undetectable PSA (

The researchers stratified men based on baseline values ​​from the Expanded Prostate Cancer Index Composite (EPIC) and whether they had received androgen deprivation therapy in the previous 6 months.

They randomly assigned 144 men to hypofractionated radiation therapy consisting of 62.5 Gy on the prostate bed administered in 25 fractions of 2.5 Gy. The other 152 men received conventional radiation therapy consisting of 66.6 Gy given in 37 fractions of 1.8 Gy.

The study protocol excluded men who had received lymph node irradiation.

Change scores – defined as the 24-month score minus the baseline score – in the urogenital and GI domains of EPIC served as co-primary endpoints.

The results showed no statistically significant or clinically meaningful difference in the mean urogenital change score from baseline to any of the four predetermined assessment points – end of radiation therapy, 6 months, 12 months or 24 months.

The results showed a statistically significant difference in the mean GI change score from baseline to the end of radiation therapy between the hypofractionated and conventional radiation therapy groups (mean –15 vs. –6.8; P. .01). However, the results showed no significant differences in mean GI change scores between baseline and 6 months, 12 months, or 24 months.

“Short-term side effects of radiation therapy are known and patients understand that,” Buyyounouski said in the press release. “Ultimately, what patients want to know is whether the side effects go away, and we saw that in our study. There was some increase in intestinal side effects – more on the shorter treatment – but after 6 months these side effects disappeared and patients reported no further or additional intestinal or bladder side effects 1 and 2 years later. “

Based on the results, it may be possible to adjust treatment techniques to reduce the GI symptoms patients reported at the end of treatment, Buyyounouski said.

The median follow-up for censored patients was 2.1 years. At this point, the researchers reported no difference between the hypofractionated and conventional radiation therapy groups in terms of local failure (2-year actuariality, 0.7% vs. 0.8%) or biochemical failure (2-year actuariality, Dec. % vs. 8%).

“Having radiation therapy after prostatectomy with fewer treatments is an asset when it comes to reducing the burden of prostate cancer on society,” Buyyounouski said. “For patients, fewer treatments mean less time, which improves access to potentially curative treatment, reduces travel costs and co-payments, and takes less time from work and other responsibilities. In addition, providers can improve the productivity of their facility and increase the overall capacity for all patients. And for the payers, fewer treatments mean lower costs. “



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