# EORTC 22991

Source: https://onco.cc/trials/eortc-22991/  
OnCo record `eortc-22991` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Six months of hormone therapy added to modern dose-escalated radiotherapy roughly halves the chance the PSA comes back, at every radiation dose tested.

## Summary

EORTC 22991 randomised 819 men, median age 70, of whom 74.8 percent were intermediate risk and 24.8 percent high risk, to radiotherapy alone or radiotherapy with 6 months of androgen suppression given as two 3-monthly depot injections of a luteinising hormone-releasing hormone agonist starting on the first day of radiotherapy. Each centre chose its radiation dose: 70, 74 or 78 Gy.

At a median 7.2 years and with 319 events, androgen suppression significantly improved biochemical disease-free survival, hazard ratio 0.52 (95 percent confidence interval 0.41 to 0.66, p<0.001), and clinical progression-free survival, hazard ratio 0.63 (0.48 to 0.84, p=0.001) with 205 events. Overall survival data were not mature at that analysis.

The exploratory analysis that matters clinically found no statistically significant interaction between the effect of androgen suppression and the radiation dose (heterogeneity p=0.79 for biochemical disease-free survival and p=0.66 for progression-free survival). Dose escalation does not remove the need for hormone therapy, which is the question the trial was designed to answer.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-25
- Also known as: EORTC 22991
- Registry id: NCT00021450
- Phase: 3
- Setting: Intermediate-risk or high-risk localised prostate cancer, cT1b-c with PSA 10 or more or Gleason 7 or more, or cT2a: radiotherapy at a centre-chosen dose of 70, 74 or 78 Gy, with or without 6 months of androgen suppression started on day 1, with biochemical disease-free survival as the primary endpoint
- Sponsor: European Organisation for Research and Treatment of Cancer
- Enrolled: 819
- Result: Six months of androgen suppression added to radiotherapy improved biochemical disease-free survival (hazard ratio 0.52, 95 percent confidence interval 0.41 to 0.66) and clinical progression-free survival (0.63, 0.48 to 0.84), with no interaction with radiation dose.
- Outcomes: Biochemical disease-free survival: Radiotherapy with 6 months of androgen suppression vs Radiotherapy alone, HR 0.52; Clinical progression-free survival: Radiotherapy with 6 months of androgen suppression vs Radiotherapy alone, HR 0.63
- Replication: RTOG 94-08 showed an overall survival benefit for 4 months of androgen suppression in the same risk band, and DART 01/05 GICOR showed that longer suppression adds more in high-risk disease.

## Sources

- ClinicalTrials.gov NCT00021450: https://clinicaltrials.gov/study/NCT00021450
- EORTC 22991 (Journal of Clinical Oncology 2016): https://doi.org/10.1200/JCO.2015.64.8055

## 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/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- technologies: [Androgen deprivation & AR pathway inhibitors](https://onco.cc/technologies/androgen-deprivation/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/)
- companies: [EORTC](https://onco.cc/companies/curie-nki-eortc/)
- terms: [Androgen deprivation therapy (ADT)](https://onco.cc/terms/adt/), [Biochemical recurrence (BCR)](https://onco.cc/terms/biochemical-recurrence/), [Curative intent vs palliative intent](https://onco.cc/terms/curative-intent/)
- trials: [DART 01/05 GICOR](https://onco.cc/trials/dart-01-05-gicor/), [EORTC 22863](https://onco.cc/trials/eortc-22863/), [RTOG 94-08](https://onco.cc/trials/rtog-9408/)

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