# CAO/ARO/AIO-12

Source: https://onco.cc/trials/cao-aro-aio-12/  
OnCo record `cao-aro-aio-12` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A German trial that tested whether chemotherapy should come before or after chemoradiotherapy. Afterwards gave more complete responses, which matters for keeping the rectum.

## Summary

CAO/ARO/AIO-12 randomised 311 patients (306 evaluable) with locally advanced rectal cancer to chemoradiotherapy preceded by three cycles of FOLFOX (group A, induction) or followed by three cycles (group B, consolidation). Pathological complete response in the intention-to-treat population was 17 percent in group A and 25 percent in group B; only group B met the predefined statistical hypothesis. Compliance with chemoradiotherapy was better in group B and compliance with chemotherapy better in group A, and the longer interval to surgery in group B (median 90 against 45 days) did not increase surgical morbidity. The result is why consolidation chemotherapy, not induction, is the sequence used when organ preservation is the aim, the same conclusion OPRA reached for watch and wait.

## Fields

- Kind: Trial
- Status: mixed
- Last checked: 2026-09-24
- Registry id: NCT02363374
- Phase: 2
- Setting: Locally advanced rectal cancer: chemoradiotherapy with induction chemotherapy before it, or consolidation chemotherapy after it
- Sponsor: German Rectal Cancer Study Group (Claus Rödel)
- Enrolled: 311
- Result: Pathological complete response 25 percent with consolidation chemotherapy against 17 percent with induction.
- Outcomes: Pathological complete response: Induction chemotherapy then chemoradiotherapy 17 percent vs Chemoradiotherapy then consolidation chemotherapy 25 percent
- Replication: OPRA found the same direction: consolidation chemotherapy gave higher TME-free survival than induction, 53 against 41 percent at three years and 54 against 39 percent at five.

## Sources

- ClinicalTrials.gov NCT02363374: https://clinicaltrials.gov/study/NCT02363374
- CAO/ARO/AIO-12: chemoradiotherapy plus induction or consolidation chemotherapy as total neoadjuvant therapy (Journal of Clinical Oncology 2019): https://doi.org/10.1200/JCO.19.00308

## Connected records

- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Rectal cancer](https://onco.cc/cancers/rectal-cancer/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/)
- drugs: [Fluorouracil (5-FU)](https://onco.cc/drugs/fluorouracil/), [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [Oxaliplatin](https://onco.cc/drugs/oxaliplatin/)
- terms: [Chemoradiation (chemoradiotherapy, CRT)](https://onco.cc/terms/chemoradiation/), [Clinical complete response (cCR)](https://onco.cc/terms/clinical-complete-response/), [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/)
- trials: [CAO/ARO/AIO-94 (German Rectal Cancer Study)](https://onco.cc/trials/cao-aro-aio-94/), [OPRA](https://onco.cc/trials/opra/), [PRODIGE 23](https://onco.cc/trials/prodige-23/), [PROSPECT (Alliance N1048)](https://onco.cc/trials/prospect/)

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