After a comprehensive systematic review of literature
published from 1996 to 2007, an American Society of Clinical Oncology panel
concluded that there is not enough clinical evidence to construct a guideline
for the use of radiofrequency ablation for patients with extrahepatic
colorectal cancer.
A clinical evidence review was published online Oct. 19
in the Journal of Clinical Oncology.
The panel reviewed 245 articles collected in Medline and
the Cochrane Library to develop the evidence review of the use of
radiofrequency ablation in colorectal cancer. The panel considered the efficacy
of surgical hepatic resection vs. radiofrequency ablation for resectable
tumors, the utility of radiofrequency ablation for unresectable tumors and
which radiofrequency ablation technique — open, laparoscopic or
percutaneous — was optimal.
Its recommendations were based on evidence from
single-arm, retrospective and prospective trials. No randomized controlled
trials were included in the review because radiofrequency ablation has not
undergone such a trial. The panel concluded that “there are no compelling
data to guide use of radiofrequency ablation in patients with viable
extrahepatic disease” and “radiofrequency ablation in the setting of
known extrahepatic disease is not supported by data at this time.”
Al B. Benson III, MD, associate director for
clinical investigation at the Robert H. Lurie Comprehensive Cancer Center of
Northwestern University and a member of the panel that drafted the guidelines,
said there is a lack of level-one evidence.
“There is extensive literature, but the literature
is what we consider observational,” Benson told HemOnc Today. “When
you have regimens that can improve survival for metastatic disease and you have
surgical resection for metastatic disease that is curative in some cases, there
is a need to define where other local interventions such as radiofrequency
ablation fit into the mix. The only way we’re going to find out is not by
doing simple observational studies but by conducting comparative trials.”
ASCO did not go so far as to discourage use of
radiofrequency ablation until the device is more rigorously tested, and Benson
said it would be difficult to phase out a treatment that has been in use for
years.
The panel noted that patient reluctance to join trials,
reluctance on the part of physicians to recommend enrollment to their patients
and limited resources are obstacles to conducting more clinical trials. Benson
said only 3% to 5% of patients with cancer participate in clinical trials, but
designing a randomized, controlled trial to test the efficacy and utility of
radiofrequency ablation would not be difficult. The panel suggested eight such
trials, including a comparison between hepatic resection vs. radiofrequency
ablation for resectable colorectal metastases or comparing systemic
chemotherapy vs. radiofrequency ablation for liver-predominant colorectal
cancer.
“This reflects, in part, questions that have been
raised because of the current utilization of this technology,” Benson
said. “Clinically, radiofrequency ablation is being used, but we
don’t have a definitive answer about how much it improves outcomes for
patients compared with chemotherapy in this specific case. Without these types
of trials, we cannot adequately define the appropriate role for RFA in this
population.”
Benson said medical devices are not tested as rigorously
as other therapies for a variety of reasons, including commercial concerns. The
panel urged manufactures of medical devices to take note of this review and
allow prospective, randomized trials to define optimal use.
He wants the FDA to demand stronger testing of equipment
such as radiofrequency ablation.
“We should see a shift when you have a device that
is actually a therapy from which we would expect a certain level of efficacy.
If you’re expecting a certain level of efficacy, then you should do
comparative trials.” – by Jason Harris
Wong SL. J Clin Oncol.
2009;doi:10.1200/JCO.2009.23.4450.