Moderate hypofractionation 70 Gy/28 fx, 10-year outcomes
ForLocalized prostate cancer, all NCCN risk groups, definitive RT ± ADT
TL;DR10-yr bRFS 71%, cRFS 86%, PCSM 6.8% after 70 Gy/28 fx IMRT for localized prostate cancer; late G≥3 GU 2%, GI 1%.
Failure after 70 Gy/28 fx was almost entirely distant: 117 of 125 clinical failures were metastatic, 8 local-only. The HR 10-yr bRFS of 42% came with only 5/244 HR pts receiving elective nodal RT, which the authors attribute to short ADT and rare nodal coverage rather than inadequate prostate dose.
In localized low and intermediate-risk prostate cancer, this supports 70 Gy/28 fx IMRT with daily IGRT as a durable schedule past 10 yr; it does not settle HR disease treated with short ADT and no pelvic nodal RT.
Failure after 70 Gy/28 fx was almost entirely distant (117 of 125 clinical failures; 8 local-only), so prostate dose is not the HR weak point. Low late toxicity was achieved with rectal/bladder V70 held to 5%, far tighter than NRG-GU005 allows, which gates whether the 2%/1% rates transfer.
12 details 3 trials watching
Single-institution consecutive series from a prospectively maintained registry, 854 pts treated 1998-2012. Median follow-up 11.3 yr (max 19). Not randomized; no comparator arm.
Biopsy-proven, clinically localized prostate adenocarcinoma across all NCCN risk groups: 266 LR, 238 FIR, 106 UIR, 244 HR. Median age 68, median PSA 8.6 ng/mL. ADT in 61%, mostly 1-6 mo.
70 Gy/28 fx at 2.5 Gy/fx, IMRT with daily IGRT (BAT ultrasound 94.8%). CTV prostate alone for LR, plus proximal SV for IR/HR; PTV margin 4-10 mm. Elective pelvic nodes in only 5 of 244 HR pts.
Whole-cohort 10-yr bRFS 71%, cRFS 86%, OS 69%, PCSM 6.8%. Of 125 clinical failures, 117 were distant and 8 local-only.
| Endpoint | LR | FIR | UIR | HR | p |
|---|---|---|---|---|---|
| bRFS | 88% | 78% | 71% | 42% | <.0001 |
| cRFS | 95% | 91% | 85% | 72% | <.0001 |
| PCSM | 2% | 5% | 5% | 15% | n/a |
10-yr late G≥3 GU 2% (mostly urethral stricture) and G≥3 GI 1% (mostly rectal bleeding). One grade 5 event each in GU and GI. 119 pts (14%) developed a new cancer, lung most common.
Authors place this alongside RTOG 0415, CHHiP, PROFIT, HYPRO and the MDACC series, none with 10-yr outcomes at publication. RTOG 0415 used the same 70 Gy/28 fx with G3 toxicity 3% to 4% at 5 yr, under looser dose-volume constraints and without mandatory IMRT.
Toxicity was physician-reported from retrospective chart review, likely underreporting events. Institutional constraints (rectal/bladder V70 5%, up to 10%) are far tighter than NRG-GU005 allows, so the toxicity rates may not hold under trial or community constraints.
The schedule controls the prostate well over 10+ yr; the risk-group gradient is driven by distant failure. What is left open is whether HR outcomes improve with longer ADT and nodal coverage at this fractionation.
Single-institution nonrandomized cohort without a comparator arm; long follow-up adds durability to randomized hypofractionation data but cannot establish equivalence on its own.
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- Toxicity reproducibility under looser multi-institutional dose constraints n=400 · primary completion 2029-02 · 70 Gy/28 fx vs 60 Gy/20 fx, intact T1-3N0M0
- Whether tighter modern IGRT margins preserve low local failure
📚 Sources · 📄 1 paper
The longer read
The value of this series lies in its follow-up, not its design. When it was reported, the randomized moderate hypofractionation trials (CHHiP, PROFIT, HYPRO, RTOG 0415) had established non-inferiority at roughly five to six years, and the remaining worry was late: does a 2.5 Gy/fx schedule produce late urethral or rectal injury, or late biochemical failure, after the trials stop reporting? A median of 11.3 years and a maximum near two decades speaks directly to that worry, and the answer here is reassuring. Late G≥3 GU of 2% and GI of 1% at 10 years is at the low end of anything reported for this dose. The figure read of G≥3 GU at 3.7% by 15 years suggests urethral events keep accruing slowly, which matters for a younger pt choosing a schedule.
The oncologic data need to be read through the pattern of failure. Of 125 clinical failures, 117 were distant and 8 were local-only. That is the strongest RT-relevant signal in the paper: at this EQD2 the prostate itself is rarely where the disease comes back. The poor HR result (10-yr bRFS 42%, PCSM 15%) therefore does not argue against the fractionation. It argues that the HR cohort was undertreated by modern standards, with elective nodal RT in only 5 of 244 pts and most ADT courses at 6 months or less. The authors now use at least 2 years of ADT and selectively treat pelvic nodes to 50.4 Gy/28 fx by simultaneous integrated boost, but this paper does not report outcomes with that approach, so the HR numbers should not be quoted as the expected outcome of hypofractionation in HR disease.
Three features should temper confidence in the toxicity figures. First, they were captured by retrospective chart review, physician-reported, without validated instruments; underreporting runs in the favorable direction. Second, the dose constraints are unusually strict: rectal and bladder V70 held to 5% (acceptable to 10%) against NRG-GU005 allowing rectal V70 25% and bladder V70 35%. A center reproducing the schedule under trial or looser constraints should expect rates closer to the 3% to 4% at 5 years the authors cite from RTOG 0415. Third, this is a single high-volume institution with standardized planning, and the authors themselves flag that multi-institutional reproducibility is unclear.
The technical era cuts both ways. Image guidance was ultrasound in 94.8% and PTV margins ran 4 to 10 mm. Modern fiducial or CBCT-based IGRT with tighter margins should lower toxicity further, but it also narrows coverage, and a series dominated by ultrasound alignment cannot tell us whether smaller margins preserve the low local failure rate.
What this changes: little for practice that has already adopted moderate hypofractionation on randomized evidence, but it removes much of the residual concern about late events past the trials' reporting window for low and intermediate-risk localized disease. What it does not settle is the HR question, where the confounding by short ADT and absent nodal coverage makes the outcome data uninformative about the schedule itself.