Lower GI: Preoperative versus postoperative chemoradiotherapy
Free question published 14 August 2026
A clinical oncology trainee is asked at an MDT to justify why locally advanced rectal cancer is treated with chemoradiotherapy before, rather than after, surgery. The German CAO/ARO/AIO-94 trial is cited as the pivotal evidence. Which statement best summarises the key result of that trial that underpins current practice?
- APreoperative chemoradiotherapy reduced local relapse incidence compared with postoperative chemoradiotherapy
- BPreoperative chemoradiotherapy increased the rate of sphincter-sparing surgical procedures but significantly worsened local control outcomes
- CThere was no difference in local recurrence, but preoperative treatment improved overall survival
- DPreoperative chemoradiotherapy significantly improved overall survival compared with postoperative chemoradiotherapy
- EPostoperative chemoradiotherapy reduced distant metastases compared with the preoperative approach
Why A is correct
The German CAO/ARO/AIO-94 trial showed a persisting reduction in local relapse with preoperative compared with postoperative chemoradiotherapy (10-year local relapse 7.1% vs 10.1%, P = .048), with no difference in overall survival (59.6% vs 59.9%, P = .85). Improved local control plus reduced toxicity established preoperative chemoradiotherapy as the standard.
And why the others are not
- BIncorrect. Preoperative treatment improved, rather than worsened, local control.
- CIncorrect. There was a significant difference in local recurrence favouring preoperative treatment, and overall survival did not differ.
- DIncorrect. Overall survival was essentially identical between arms (59.6% vs 59.9%, P = .85).
- EIncorrect. The trial did not show a reduction in distant metastases favouring the postoperative arm; the benefit of preoperative treatment was in local control.
Source German CAO/ARO/AIO-94 trial — preoperative versus postoperative chemoradiotherapy in rectal cancer — Sauer R, Liersch T, Merkel S, et al. Preoperative versus postoperative chemoradiotherapy for locally advanced rectal cancer: results of the German CAO/ARO/AIO-94 randomized phase III trial after a median follow-up of 11 years. J Clin Oncol. 2012.
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