22 Pages of Nothing
I was very amused (and slightly horrified) by the Cochrane Hepato-Biliary group’s most recent offering regarding surgical resection versus liver transplantation for hepatocellular carcinoma. The 22-page review details elegantly the background to the review, gives an in depth search strategy and description of excluded studies and then concludes:
“There are no randomised clinical trials comparing surgical resection and liver transplantation for hepatocellular carcinoma treatment.”.
Recent evidence suggests that a chocolate teapot may me marginally more useful.
The whole idea of a systematic review is to summarise the best available evidence for an intervention. Whilst the ideal outcome would be to identify a large body of RCT data, this is usually not the case but that does not necessarily mean that there is no value to the evidence that is available. Knowing what work has been previously performed in the area of interest, even if studies are not randomised, can sometime provide useful information about a potential treatment effect, and even if not may provide useful data upon which to base future studies. Indeed, the Cochrane Collaboration’s own GRADE approach allows for the upgrading of non-randomised evidence if effect sizes are large and there is no discernable bias.
To my mind, if a literature search identifies no randomised controlled trials relevant to the intervention under investigation, then the next available level in quality of trial should be appraised. Often, firm conclusions will be impossible to make, in which case rather than uselessly stating “no trials were found”, the available evidence can be used to suggest a specific and realistic trial that could be performed in order to fill the identified gap in the evidence.
Incidently, our own group reviewed the evidence for transplantation in hepatic malignancy back in 2007, identifying 5 retrospective studies comparing resection and transplantation in patients with Childs A cirrhosis and HCC. These trials supported the idea that disease free survival is improved with transplantation, but that there is no great evidence for an improvement in overall survival. The suggestion is that the benefits in terms of removing the diseased liver tissue are offset by the surgical risk and risks of lifelong immunosuppression with transplantation. We recommended an RCT of transplantation versus resection for patients with normal hepatic function, utilising an ITT analysis to account for progression whilst on the transplant waiting list.
