Letter to the Editor: Multibipolar radiofrequency ablation for hepatocellular carcinoma - a superior thermal ablation technique or a reflection of operator excellence?

Abstract

This correspondence critically reassesses Bahloul et al’s comparison of multibipolar radiofrequency ablation (mbp-RFA) vs microwave ablation (MWA) for hepatocellular carcinoma. While mbp-RFA showed lower local tumor progression (11.4% vs 25.2%), we argue that the near-collinear allocation of techniques across institutions, marked differences in operator experience (303 vs 107 months), and unmeasured peritumoral fibrosis likely confound the results. The MWA outcomes appear below contemporary high-power series, raising generalizability concerns. We contend that the findings reflect institutional expertise and precision execution rather than inherent technical superiority of mbp-RFA. Rigorous prospective trials incorporating peritumoral tissue characterization and ablation margin assessment are needed before abandoning simpler, faster MWA.

Key Words: Hepatocellular carcinoma; Thermal ablation; Confounding by indication; Operator experience; Peritumoral fibrosis

Core Tip: The study by Bahloul et al suggests that multibipolar radiofrequency ablation may achieve better local control than microwave ablation for hepatocellular carcinoma, particularly in tumors ≥ 3 cm. However, significant confounders, such as operator experience and institutional variation, limit causal interpretation. Rather than confirming technical superiority, these findings underscore the importance of procedural expertise, tumor biology, and ablation precision. Future research should focus on randomized trials, peritumoral tissue characterization, and standardized quality metrics to guide personalized treatment selection.

TO THE EDITOR

We read with great interest the recent study by Bahloul et al[1] published in the World Journal of Gastroenterology comparing multibipolar radiofrequency ablation (mbp-RFA) against microwave ablation (MWA) for treatment-naïve hepatocellular carcinoma (HCC). Their finding that mbp-RFA significantly reduces local tumor progression (LTP)[2] (11.4% vs 25.2%, P < 0.001) challenges the prevailing clinical shift toward MWA[3]. However, as a retrospective, two-institutional study with near-collinear allocation of techniques, we believe the conclusions warrant a more cautious interpretation. While the authors acknowledge several limitations, we argue that the intertwined effects of operator proficiency, institutional protocol, and the overlooked tumor microenvironment may collectively explain a substantial portion of the observed difference, potentially confounding the purported technical supremacy of mbp-RFA.

Our primary concern centers on the inseparable coupling between technique and institutional expertise. The data reveal that mbp-RFA was predominantly performed at Institution A by operators with significantly greater median experience (303 vs 107 months, P = 0.026), while the majority of MWA cases (76.2%) were performed at Institution B. This is not merely a statistical nuisance, it is a classic case of confounding by indication and skill. The authors argue that multivariate analysis dismissed operator experience as an independent predictor. However, using total career months as a surrogate for proficiency is inherently crude; it fails to capture case-volume variability, learning-curve dynamics specific to each modality, or the nuanced spatial planning required for multi-needle mbp-RFA. In essence, the study may primarily reflect the outcomes achievable at a high-volume, mbp-RFA-specialized center, rather than proving a universal advantage of the technology itself. The excellent MWA outcomes from Institution B further suggest that institutional protocols and baseline expertise, rather than the generator, are the dominant drivers of success.

Second, while the study meticulously adjusted for tumor size and liver function, it overlooked a critical biological moderator: The peritumoral parenchyma. Emerging multicenter evidence indicates that peritumoral fibrosis acts as a natural barrier, significantly reducing LTP risk after thermal ablation[4]. This variable is not merely academic. If patients in the mbp-RFA group (which had a higher proportion of larger tumors ≥ 3 cm) harbored more fibrotic peritumoral halos, this could create a biological advantage independent of the energy modality. MWA’s spherical ablation zone, though efficient, may not conform as precisely to irregular fibrotic rims as the multi-needle “no-touch” configurational approach of mbp-RFA. Without histologic or imaging-based characterization of the peritumoral milieu, attributing the lower LTP solely to mbp-RFA’s physical properties remains speculative.

Third, and most importantly for clinical translation, the generalizability of these results is questionable. The 26.0% LTP rate for MWA in tumors ≥ 3 cm, while aligning with some cohorts, appears higher than contemporary series using high-power MWA (> 100W) or fusion imaging guidance, which report 1-year LTP-free survivals exceeding 95%[5]. This raises the possibility that the MWA outcomes in this study represent a performance benchmark at a single institution, rather than the ceiling of what MWA can achieve. The adoption of mbp-RFA requires substantial capital investment, specialized training, and prolonged procedural time, barriers that may outweigh its marginal benefit for smaller tumors in average-volume centers. Until a prospective randomized trial, standardized by ablation margin volume and tumor biology, directly compares mbp-RFA against state-of-the-art high-power MWA, we risk prematurely relegating a simpler, faster, and more widely available technology.

In conclusion, Bahloul et al[1] have delivered an invaluable, thought-provoking dataset. However, their findings should be interpreted as a testament to the power of precision execution and institutional focus, rather than as conclusive evidence for the technical superiority of mbp-RFA. The future of ablation oncology lies not in declaring a single winning technology, but in dissecting the interplay between energy delivery, operator skill, and tumor biology to select the right tool for the right patient. We advocate for rigorous prospective trials that incorporate peritumoral tissue characterization and quantitative ablation margin assessment to resolve these critical uncertainties.