# CLOCC

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

## TL;DR

The only randomised trial to show that burning out liver metastases, rather than just giving chemotherapy, lets more people survive eight years.

## Summary

CLOCC randomised 119 patients with unresectable colorectal liver metastases to systemic treatment plus radiofrequency ablation (with resection where possible) or to systemic treatment alone. The trial closed early for slow accrual and was reported as a randomised phase 2 study. At a median follow-up of 9.7 years, 39 of 60 patients in the combined modality group had died against 53 of 59 in the systemic group; overall survival favoured local treatment (hazard ratio 0.58, 95% CI 0.38 to 0.88, p=0.01). Eight-year overall survival was 35.9 against 8.9 percent, and median overall survival 45.6 against 40.5 months. Small and underpowered, CLOCC is nonetheless the only randomised evidence that ablation of liver metastases lengthens life, and it underpins the aggressive local treatment of oligometastatic colorectal cancer.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-24
- Also known as: EORTC 40004
- Registry id: NCT00043004
- Phase: 2
- Setting: Unresectable colorectal liver metastases: systemic chemotherapy with radiofrequency ablation and optional resection, against systemic chemotherapy alone
- Sponsor: European Organisation for Research and Treatment of Cancer
- Enrolled: 119
- Result: Eight-year overall survival 35.9 against 8.9 percent with ablation added (hazard ratio 0.58).
- Outcomes: Overall survival at 8 years: Chemotherapy plus radiofrequency ablation 35.9 percent vs Chemotherapy alone 8.9 percent, HR 0.58

## Sources

- ClinicalTrials.gov NCT00043004: https://clinicaltrials.gov/study/NCT00043004
- CLOCC: local treatment of unresectable colorectal liver metastases, randomised phase 2 trial (Journal of the National Cancer Institute 2017): https://doi.org/10.1093/jnci/djx015

## Connected records

- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [Microwave and radiofrequency ablation systems](https://onco.cc/technologies/microwave-rf-ablation/), [Thermal ablation (RFA, microwave, cryo)](https://onco.cc/technologies/thermal-ablation/)
- drugs: [Bevacizumab](https://onco.cc/drugs/bevacizumab/), [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [Oxaliplatin](https://onco.cc/drugs/oxaliplatin/)
- companies: [EORTC](https://onco.cc/companies/curie-nki-eortc/)
- terms: [Hepatectomy (liver resection)](https://onco.cc/terms/hepatectomy/), [Oligometastatic disease](https://onco.cc/terms/oligometastatic/), [Radiofrequency ablation (RFA)](https://onco.cc/terms/radiofrequency-ablation/)

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