Recently, Vouche et al. reported their experience with segmental transarterial yttrium 90 radiation (STAY90R) as a potential curative option for unresectable solitary hepatocellular carcinomas (HCCs) ≤5 cm not amenable to radiofrequency ablation (RFA). However, careful analysis of the study's results calls for some comments.
First, almost half of the patients were Child-Pugh-B and one-third underwent liver transplantation (LT) a short time after STAY90R. In this setting, relevant comparison of overall and local tumor progression-free survivals after STAY90R with those reported after RFA should require a specific analysis in Child-Pugh-A patients censored to LT (no more risk of local recurrence after LT).
Beyond the difficulty to assess the response to STAY90R with imaging, the question is how to know if such a method has enough reliable and predictable antitumor effects to be used like RFA for curative purposes. Vouche et al. pointed out that 51% of HCC ≤5 cm showed complete necrosis (CN) at histopathological examinations after STAY90R, a result that they assume is quite similar to after RFA. Mazzaferro et al. have nicely shown that time to transplantation (TTT) was strongly associated with a dramatic increase in the probability to find viable tumor in the ablation zone (∼30%/3 months of waiting time). The TTT was shorter in the Vouche et al. study (6.3 months [3.6-9.7]) compared to the RFA studies of Mazzaferro et al. (9.5 months [2-47]) and Lu et al. (7.5 months [0.5-21.1]).[2, 3] Therefore, the direct comparison based on CN between STAY90R and RFA made by Vouche et al. appears spurious. Moreover, focusing on HCCs ≤3 cm, 54.1% of CN are reported by Vouche et al., while it was up to 63% in the Mazzaferro et al. and 83% in Lu et al. studies. The superiority of RFA in achieving CN of small HCCs becomes more obvious when one considers no-touch multipolar RFA, which achieved up to 89.6% of CN of HCC ≤5 cm with 8.4 months median TTT. In addition, as Vouche et al. did not report histologic data concerning the nontumorous liver, the comparison of the method to segmentectomy appears to be somewhat overstated.
Finally, for nonresectable small HCC, a clear definition of tumors not amenable to RFA is critical because such a judgment leads to treatments with a higher risk of incomplete response. Vouche et al. pointed out the potential technical limitations of RFA related to specific locations. However, currently most of these limitations could be overcome and therefore are no longer regarded as definite contraindications in expert centers. Only a central location abutting primary main bile ducts remains a common contraindication for thermotherapy like RFA.
In conclusion, Vouche et al. showed that STAY90R can induce CN in roughly 50% of HCC ≤5 cm. Thus, STAY90R could be regarded only as one of the second-line intraarterial treatments in the very rare cases of small HCCs not amenable to resection or RFA.
Olivier Seror, M.D., Ph.D.
Jean-Charles Nault, M.D., Ph.D.
Pierre Nahon, M.D., Ph.D.
Gisele N'Kontchou, M.D.
Jean-Claude Trinchet, M.D., Ph.D.
Hôpital Jean Verdier
Groupe des Hopitaux Universitaires Paris Saint Denis
Assistance Publique Hôpitaux de Paris, Radiology