# ACNS0121

Source: https://onco.cc/trials/acns0121/  
OnCo record `acns0121` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

ACNS0121 showed that focused radiotherapy to the tumour bed straight after surgery cures most children with ependymoma, including those under three who used to be denied radiotherapy, and that children whose tumour could not be fully removed do far worse even with chemotherapy and a second operation.

## Summary

ACNS0121 was a Children's Oncology Group phase 2 trial of 378 children with newly diagnosed ependymoma, assigned by extent of resection and histology. Children with completely resected, differentiated supratentorial tumours were observed; those with near-total or gross-total resection received immediate post-operative conformal radiotherapy to 59.4 Gy (54 Gy under 18 months); those with subtotal resection received chemotherapy (vincristine, carboplatin, cyclophosphamide, etoposide) before second-look surgery and radiotherapy. The primary endpoint was event-free survival.

Five-year event-free survival was 68.5 percent after immediate conformal radiotherapy, 61.4 percent in the observation group and 37.2 percent after subtotal resection. Outcomes were similar for children under three, tumour grade mattered, and 1q gain in posterior fossa tumours predicted relapse (five-year event-free survival 47.4 against 82.8 percent). The corpus's ependymoma page describes maximal resection followed by conformal or proton radiotherapy to the tumour bed as the ACNS0121 approach.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-22
- Also known as: COG ACNS0121
- Tags: soc-trials
- Registry id: NCT00027846
- Phase: 2
- Setting: Newly diagnosed localised ependymoma in children aged 1 to 21: observation after complete resection of differentiated supratentorial tumours, immediate conformal radiotherapy after near-total or gross-total resection, and chemotherapy before second surgery and radiotherapy after subtotal resection
- Sponsor: Children's Oncology Group
- Enrolled: 378
- Result: Five-year event-free survival 68.5 percent with immediate post-operative conformal radiotherapy, 61.4 percent with observation after complete resection of differentiated supratentorial tumours, and 37.2 percent after subtotal resection with chemotherapy, second surgery and radiotherapy.
- Outcomes: Event-free survival at 5 years by treatment group: Near-total or gross-total resection then immediate conformal radiotherapy 68.5% vs Observation after complete resection of differentiated supratentorial ependymoma 61.4% vs Subtotal resection: chemotherapy, second surgery, radiotherapy 37.2%; Event-free survival at 5 years, infratentorial tumours by 1q status: Without 1q gain 82.8% vs With 1q gain 47.4%

## Sources

- ClinicalTrials.gov NCT00027846: https://clinicaltrials.gov/study/NCT00027846

## Connected records

- cancers: [Brain and spinal cord tumours (all types)](https://onco.cc/cancers/brain-tumours/), [Childhood cancers (all types)](https://onco.cc/cancers/childhood-cancers/), [Ependymoma](https://onco.cc/cancers/ependymoma/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/)
- drugs: [Carboplatin](https://onco.cc/drugs/carboplatin/), [Cyclophosphamide](https://onco.cc/drugs/cyclophosphamide/), [Etoposide](https://onco.cc/drugs/etoposide/), [Vincristine](https://onco.cc/drugs/vincristine/)
- institutions: [Children's Oncology Group (COG)](https://onco.cc/institutions/childrens-oncology-group/)
- key papers: [ACNS0121: conformal radiotherapy for paediatric ependymoma, chemotherapy for incompletely resected tumours and observation after complete resection](https://onco.cc/key-papers/paper-acns0121-ependymoma-conformal-radiotherapy-merchant-jco-2019/)

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