Ablation vs SBRT for the Management of HCC
Ablation and stereotactic body radiation therapy (SBRT) are both effective treatments for patients with hepatocellular carcinoma (HCC), especially those in early stages of the disease. Siddharth A. Padia, MD explains what interventional radiologists need to know when deciding between ablation and SBRT for HCC.
Many patients with HCC will develop new tumors and/or have cirrhosis progression in the future so minimizing the risk of major complications and preserving as much normal liver parenchyma as possible is important so patients may be candidates for future liver directed therapy.
“Ablation is part of all HCC treatment algorithms. When done appropriately, it has an exceptional safety profile,” Dr Padia said.
Ablation has a long track-record of success, including publication of numerous trials across many centers, and thus, is generally preferred over SBRT. However, when patients are selected appropriately, studies have shown equivalent rates of survival to surgical resection, Dr Padia said.
When deciding between ablation and SBRT, providers should take into consideration which treatment may be most beneficial for individual patients. For example, because ablation is typically performed under general anesthesia in the United States, patients with significant cardiovascular comorbidities should not be considered. In these cases, SBRT may be a better treatment option because it does not typically involve sedation.
Another example Dr Padia highlights is that patients need to make frequent visits for SBRT whereas ablation typically requires only a single visit. This may impact what treatment is ultimately best suited for a patient.
Other criteria to consider when deciding between ablation and SBRT include tumor size and location.
“Despite the excellent efficacy of ablation, several limitations exist,” Dr Padia said. “Tumors greater than 3 cm or infiltrative tumors have been shown to demonstrate higher local tumor recurrence rates. Certain tumor locations make ablation either very challenging or potentially dangerous. For example, thermal ablation for tumors in the porta hepatis can results in potential fatal biliary injury. In these scenarios, SBRT may be a safer option with potential for long-term tumor control.”
Studies to Consider
There are currently 3 major studies comparing ablation to SBRT for HCC.
In a single center retrospective study1 comparing SBRT to radiofrequency ablation, 332 tumors were treated with therapy chosen based on a multidisciplinary tumor board. The primary endpoint, freedom from local tumor progression, was superior in the SBRT arm (97% vs 84% at 1 year). “However, the definition of local tumor progression was different between the 2 treatment groups. For SBRT, standard RECIST criteria was used, which defines progression as increase in the longest diameter of the tumor. In contrast, modified RECIST was used for ablation, which simply marks progression at the sign of increasing arterial enhancement, not necessarily overall size,” Dr Padia said.
The second study2 utilized National Cancer Database data from 1500 US hospital, covering approximately 70% of all new cancer diagnoses, with a total of 29 million unique cancer cases are entered. Long-term overall survival from RFA was compared to SBRT and after propensity score matching, the 5-year survival for ablation was 30% versus 19% for SBRT, resulting in a median 10-month difference in overall survival. Moreover, the survival benefit was detected across all treatment groups, including tumors greater than 3 cm.
“One should be aware that national databases can be subject to bias based on selective data input by institutions,” Dr Padia warned.
In the third study3, rates of pathological necrosis and post-liver transplant tumor recurrence in patients undergoing pre-transplant bridging therapy with either thermal ablation, external beam radiation, or chemoembolization were compared.
“All 3 treatment modalities demonstrated equivalent rates of success to bridging to transplant, with comparatively low rates of pre-transplant dropout,” Dr Padia said. “However, during follow-up after transplant, tumor recurrence was demonstrated in 23% of the SBRT group and in 13% of the RFA group. On explant pathology, complete pathological necrosis was demonstrated in 49% of tumors in the RFA, and only in 13% of the SBRT group.”
1. Wahl DR, Stenmark MH, Tao Y, et al. Outcomes after stereotactic body radiotherapy or radiofrequency ablation for hepatocellular carcinoma. J Clin Oncol. 2010;34(5):452-459.
2. Rajyaguru DJ, Borgert AJ, Smith AL, et al. Radiofrequency ablation versus stereotactic body radiotherapy for localized hepatocellular carcinoma in nonsurgically managed patients: analysis of the national cancer database. J Clin Oncol. 2018;36(6):600-608.
3. Sapisochin G, Barry A, Doherty M, et al. Stereotactic body radiotherapy vs TACE or RFA as a bridge to transplant in patients with hepatocellular carcinoma. An intention-to-treat analysis. J Hepatol. 2017;67(1):92-99,