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Radiofrequency ablation can extend the lives of patients with inoperable liver metastases from colorectal cancer [Íîâîñòü äîáàâëåíà - 05.11.2007]

Radiofrequency ablation---a technique that involves inserting a special needle electrode into tumours to destroy them through heat from the inside---may help improve survival for patients with liver metastases from colorectal cancer whose lesions are unresponsive to chemotherapy and too widespread for surgery, according to an observational study reported in the Annals of Surgery.

25% of patients who present with colorectal cancer already have liver metastases and within 5 years of diagnosis 50% of those initially lacking obvious metastases will have evidence of cancer spread. Because this distant disease is associated with poor outcomes---less than 1% of patients with untreated liver metastases will be alive 4 years after diagnosis---and because in many patients the only site of metastases at death is the liver, effective treatment of these lesions could have substantial implications for survival.
  
The gold standard treatment for liver metastases is surgery, but in many cases resection would leave too little of the organ for physiological functioning, so is not a feasible treatment option. Other interventions that can extend life or reduce the tumour burden to a point where resection might be possible include aggressive chemotherapy, portal vein embolisation (a technique for inducing new growth in the liver enabling more tumour-involved tissue to be removed than would otherwise have been possible), and radiofrequency ablation, in which tumours are destroyed from the inside using a needle guided by ultrasound or computed tomography.
  
Encouraging data from a North American multicentre study that suggested radiofrequency ablation could extend life by an average of 2.5 years prompted Allan Siperstein and colleagues from San Francisco and Cleveland to further investigate the potential of this treatment in patients who were not candidates for surgery and in whom chemotherapy had failed. The researchers designed a prospective study of 234 patients (81 women and 153 men) who were prescribed radiofrequency ablation for metastatic colorectal adenocarcinoma over a 10-year period beginning in May 1997. All of the patients involved in the study had failed chemotherapy and had an average of 2.8 liver lesions.
  
CT scans were done before and after the procedure and the patients were assessed for their number of lesions, size and location of defects, presence of disease outside the liver, and some liver function tests. Researchers followed the progress of the patients until the study came to an end in December 2006. They noted progression of disease in the treated areas of the liver, evidence of new disease either within or outside the liver, and death. The median follow-up was 24 months and 148 patients died during the study period.
  
For the whole group, 3- and 5-year survival data showed that radiofrequency ablation produced 20.2% and 18.4% survival rates, respectively. In univariate analyses looking at the relationship between individual disease characteristics and outcomes, the researchers found that the number of liver lesions at diagnosis was statistically linked to survival. Patients presenting with fewer than 3 lesions had a median survival of 27 months versus 17 months in those presenting with more than 3 lesions. Lesion size was also found to be statistically significant: lesions smaller than 3 cm were associated with a median survival of 28 months compared with 20 months for lesions greater than 3 cm . One particularly interesting observation was the lack of a statistically significant difference in benefit from the treatment when the patients were divided up by stage of disease at presentation, leading the authors to conclude that “all patients despite initial stage derived survival benefit from RFA.”
  
Overall, the authors say of their findings: “Previous to local therapies this subgroup of patients had virtually no survivors at 5 years, whereas our study demonstrates an 18.4% 5-year survival rate.”
  
Dr David L Bartlett, Professor of Surgery and Chief of the Division of Surgical Oncology at the University of Pittsburgh , who wrote an editorial accompanying the paper, agrees that the data are encouraging. “To take a group of unresectable patients with metastatic colon cancer of the liver and provide an 18% 5-year survival, I think really cements the role of radiofrequency ablation of this disease,” he said.
  
Survival after radiofrequency ablation of colorectal liver metastases 10-year experience.
Siperstein AE, Berber E, Ballem N, Parikh RT.
Ann Surg 2007; 246: 559–67.