CAO/ARO/AIO-94
In locally advanced rectal cancer, does preoperative rather than postoperative chemoradiotherapy reduce local recurrence and improve survival?
Reported outcome visualization
Key results
At median follow-up 134 months, 10-year OS was 59.6% with preoperative versus 59.9% with postoperative CRT (P=.85). Ten-year cumulative local relapse was 7.1% versus 10.1% (P=.048).
Absolute Effect
Absolute 10-year local relapse reduction 3.0 percentage points; NNT ≈34 to prevent one local relapse by 10 years, based on the reported cumulative incidences. No OS benefit was demonstrated.
NNT: ≈34, based on 10-year local relapse.
NNH: Not quantifiable from the verified fixed-time toxicity data used in this summary; see toxicity and treatment burden below.
Time-to-event interpretation: Hazard ratios and median survival are relative/time-to-event measures; they are not converted into NNT unless a fixed-time absolute event estimate is available.
Toxicity and treatment burden
Preoperative treatment is associated with lower acute and late toxicity than postoperative CRT in the original report, and a higher likelihood of sphincter preservation in suitable patients. NNH is not quantified here without a verified single toxicity endpoint rate.
Follow-up, limitations and maturity
Follow-up: Median follow-up 134 months.
Older fluorouracil-only treatment and staging; modern MRI-based selection, total neoadjuvant therapy and organ-preservation strategies have changed care. The trial compared timing, not CRT against no CRT.
Clinical interpretation
Preoperative CRT reduces long-term local relapse and treatment toxicity compared with postoperative CRT, without a demonstrated overall-survival advantage.
Primary publication and sources
Sauer R, et al. J Clin Oncol. 2012;30:1926–1933.
Current-practice context · reviewed 15 October 2026
Preoperative treatment is preferred over postoperative CRT when pelvic radiation is indicated, but CAO/ARO/AIO-94 does not define all current management. Contemporary MRI-based risk stratification and total neoadjuvant therapy are important, particularly for lower rectal tumours or high-risk disease; selected patients with clinical complete response may discuss nonoperative management.