Background: A wide range of ablative and non-surgical therapies are available for treating small hepatocellular carcinoma in patients with very early or early-stage disease and preserved liver function.
Objective: To review and compare the effectiveness of all current ablative and non-surgical therapies for patients with small hepatocellular carcinoma (≤ 3 cm).
Design: Systematic review and network meta-analysis.
Data sources: Nine databases (March 2021), two trial registries (April 2021) and reference lists of relevant systematic reviews.
Review methods: Eligible studies were randomised controlled trials of ablative and non-surgical therapies, versus any comparator, for small hepatocellular carcinoma. Randomised controlled trials were quality assessed using the Cochrane Risk of Bias 2 tool and mapped. The comparative effectiveness of therapies was assessed using network meta-analysis. A threshold analysis was used to identify which comparisons were sensitive to potential changes in the evidence. Where comparisons based on randomised controlled trial evidence were not robust or no randomised controlled trials were identified, a targeted systematic review of non-randomised, prospective comparative studies provided additional data for repeat network meta-analysis and threshold analysis. The feasibility of undertaking economic modelling was explored. A workshop with patients and clinicians was held to discuss the findings and identify key priorities for future research.
Results: Thirty-seven randomised controlled trials (with over 3700 relevant patients) were included in the review. The majority were conducted in China or Japan and most had a high risk of bias or some risk of bias concerns. The results of the network meta-analysis were uncertain for most comparisons. There was evidence that percutaneous ethanol injection is inferior to radiofrequency ablation for overall survival (hazard ratio 1.45, 95% credible interval 1.16 to 1.82), progression-free survival (hazard ratio 1.36, 95% credible interval 1.11 to 1.67), overall recurrence (relative risk 1.19, 95% credible interval 1.02 to 1.39) and local recurrence (relative risk 1.80, 95% credible interval 1.19 to 2.71). Percutaneous acid injection was also inferior to radiofrequency ablation for progression-free survival (hazard ratio 1.63, 95% credible interval 1.05 to 2.51). Threshold analysis showed that further evidence could plausibly change the result for some comparisons. Fourteen eligible non-randomised studies were identified (n ≥ 2316); twelve had a high risk of bias so were not included in updated network meta-analyses. Additional non-randomised data, made available by a clinical advisor, were also included (n = 303). There remained a high level of uncertainty in treatment rankings after the network meta-analyses were updated. However, the updated analyses suggested that microwave ablation and resection are superior to percutaneous ethanol injection and percutaneous acid injection for some outcomes. Further research on stereotactic ablative radiotherapy was recommended at the workshop, although it is only appropriate for certain patient subgroups, limiting opportunities for adequately powered trials.
Limitations: Many studies were small and of poor quality. No comparative studies were found for some therapies.
Conclusions: The existing evidence base has limitations; the uptake of specific ablative therapies in the United Kingdom appears to be based more on technological advancements and ease of use than strong evidence of clinical effectiveness. However, there is evidence that percutaneous ethanol injection and percutaneous acid injection are inferior to radiofrequency ablation, microwave ablation and resection.
Study registration: PROSPERO CRD42020221357.
Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment (HTA) programme (NIHR award ref: NIHR131224) and is published in full in Health Technology Assessment; Vol. 27, No. 29. See the NIHR Funding and Awards website for further award information.
Keywords: HEPATOCELLULAR CARCINOMA; MICROWAVE ABLATION; NETWORK META-ANALYSIS; PERCUTANEOUS ETHANOL INJECTION; RADIOFREQUENCY ABLATION; SYSTEMATIC REVIEW.
Hepatocellular carcinoma is the most common type of primary liver cancer. There are a range of different treatments available for patients with early hepatocellular carcinoma. We looked for clinical trials in patients with small tumours (up to 3 cm) that compared different treatments. We brought together and analysed the results of these trials to see which treatments were most effective in terms of survival, progression, side effects and quality of life. Overall, the evidence has limitations; many trials had few patients and were of poor quality. Most were from China or Japan, where the common causes of liver disease and treatments available differ from those in the United Kingdom. The results of our analyses were very uncertain so we cannot be sure which treatment is the best overall. We did find that three treatments – radiofrequency ablation, microwave ablation and surgery – were generally more effective than percutaneous ethanol injection and percutaneous acid injection. There was not enough evidence to be certain which treatment was better when radiofrequency ablation was compared with laser ablation, microwave ablation, proton beam therapy or surgery. We found only poor-quality, non-randomised trials on high-intensity focused ultrasound, cryoablation and irreversible electroporation. There was very little evidence on treatments that combined radiofrequency ablation with other therapies. We found no studies that compared electrochemotherapy, histotripsy, stereotactic ablative radiotherapy or wider radiotherapy techniques with other treatments. Only two studies reported data on quality of life or patient satisfaction. We discussed the findings with patients and clinical experts. Stereotactic ablative radiotherapy was highlighted as a treatment that requires further research; however, it is only appropriate for certain subgroups of patients. Feasibility studies could inform future clinical trials by exploring issues such as whether patients are willing to take part in a trial or find the treatments acceptable.