# How many radiotherapy visits: the prostate fractionation trials

Source: https://onco.cc/terms/prostate-radiotherapy-fractionation/  
OnCo record `prostate-radiotherapy-fractionation` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Prostate cancer responds unusually well to a few large doses of radiation rather than many small ones, so a course that used to take eight weeks now takes four weeks, or two, or one.

## Summary

Prostate cancer is thought to have a low alpha/beta ratio, meaning it is more sensitive than the surrounding normal tissue to the size of each radiation dose. If that is right, giving fewer, larger fractions should control the cancer at least as well while sparing the rectum and bladder. Four randomised trials tested it and all four agreed.

Moderate hypofractionation, around 20 fractions over 4 weeks. CHHiP randomised 3,216 men to 74 Gy in 37 fractions, 60 Gy in 20 or 57 Gy in 19, all with intensity-modulated technique and most with 3 to 6 months of androgen suppression. At 5 years, 88.3 percent were free of biochemical or clinical failure on 74 Gy, 90.6 percent on 60 Gy and 85.9 percent on 57 Gy. Sixty Gy was non-inferior (hazard ratio 0.84, 90 percent confidence interval 0.68 to 1.03); 57 Gy was not (1.20, 0.99 to 1.46). Late side effects were similar. PROFIT reached the same conclusion in 1,206 intermediate-risk men without hormones, 85 percent failure-free at 5 years in both arms, and RTOG 0415 in 1,115 low-risk men, 86.3 against 85.3 percent, though there late grade 2 to 3 bowel and bladder events rose (hazard ratios 1.31 to 1.59).

Ultra-hypofractionation, five to seven fractions. HYPO-RT-PC randomised 1,180 men with intermediate-to-high-risk disease and no androgen deprivation to 42.7 Gy in seven fractions over 2.5 weeks or 78 Gy in 39 fractions over 8 weeks. Five-year failure-free survival was 84 percent in both arms, adjusted hazard ratio 1.002 (95 percent confidence interval 0.758 to 1.325). Acute symptoms were worse with the short course and late toxicity was not, except for a transient rise in urinary toxicity at 1 year (6 against 2 percent, p=0.0037). PACE-B randomised 874 men to 36.25 Gy in five fractions or to control radiotherapy, and at a median 74 months the 5-year freedom from biochemical or clinical failure was 95.8 percent with stereotactic body radiotherapy and 94.6 percent with control (hazard ratio 0.73, 90 percent confidence interval 0.48 to 1.12, non-inferior).

The honest caveat is in PACE-B's toxicity data: late grade 2 or higher genitourinary toxicity at 5 years was 26.9 percent with stereotactic radiotherapy against 18.3 percent with control (p<0.001), while gastrointestinal toxicity was the same (10.7 against 10.2 percent). A separate PACE-B analysis found that men with a higher baseline International Prostate Symptom Score (odds ratio 1.11 per point, 95 percent confidence interval 1.05 to 1.18) or already on urinary medication (2.32, 1.09 to 4.95) were more likely to have late urinary toxicity, and recommended they consider moderate hypofractionation instead.

So the choice is not simply fewer visits. It is fewer visits at the price of a somewhat higher chance of lasting urinary symptoms, and a man whose bladder already troubles him is the one who should take the longer course.

## Fields

- Kind: Term
- Status: standard-of-care
- Last checked: 2026-09-25
- Also known as: prostate hypofractionation; SBRT for prostate cancer; moderate hypofractionation prostate

## Sources

- CHHiP 5-year outcomes (Lancet Oncology 2016): https://doi.org/10.1016/S1470-2045(16)30102-4
- HYPO-RT-PC 5-year outcomes (Lancet 2019): https://doi.org/10.1016/S0140-6736(19)31131-6
- PACE-B (New England Journal of Medicine 2024): https://doi.org/10.1056/NEJMoa2403365
- PACE-B late urinary toxicity factors (European Urology 2026): https://doi.org/10.1016/j.eururo.2025.07.007

## Connected records

- cancers: [Localised prostate cancer, high and very high risk](https://onco.cc/cancers/prostate-high-risk/), [Localised prostate cancer, intermediate risk](https://onco.cc/cancers/prostate-intermediate-risk/), [Localised prostate cancer, very low and low risk](https://onco.cc/cancers/prostate-low-risk/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- technologies: [CyberKnife robotic radiosurgery](https://onco.cc/technologies/cyberknife/), [Hypofractionated radiotherapy](https://onco.cc/technologies/hypofractionated-radiotherapy/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [SBRT / SABR (stereotactic radiotherapy)](https://onco.cc/technologies/sbrt/)
- terms: [Curative intent vs palliative intent](https://onco.cc/terms/curative-intent/), [Hypofractionation (fewer, larger radiotherapy doses)](https://onco.cc/terms/hypofractionation/), [Quality of life and patient-reported outcomes (QoL, PRO)](https://onco.cc/terms/qol-pro/)
- trials: [CHHiP](https://onco.cc/trials/chhip/), [HYPO-RT-PC](https://onco.cc/trials/hypo-rt-pc/), [PACE-B](https://onco.cc/trials/pace-b/), [PARTIQoL](https://onco.cc/trials/partiqol/), [PROFIT (Prostate Fractionated Irradiation Trial)](https://onco.cc/trials/profit-trial/), [RTOG 0415](https://onco.cc/trials/rtog-0415/)

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