Conformal external beam radiation or selective internal radiation therapy-a comparison of treatment outcomes for hepatocellular carcinoma

Abstract

Background: Non-operative treatment for hepatocellular carcinoma (HCC) has expanded significantly with the use of selective internal radiotherapy (SIRT) mostly with yttrium 90 ((90)Y) tagged microspheres and highly conformal external beam radiation therapy such as stereotactic body radiotherapy (SBRT) to treat unresectable liver tumors for local tumor control. SBRT is a noninvasive procedure using external radiation source under image guidance, while SIRT delivers radioactive particles by transarterial radioembolization (TARE). However, the survival benefits of SBRT versus SIRT have never been compared. The aim of the present study is to compare the outcomes of overall and disease specific survival (DSS) using SIRT versus SBRT to treat HCC.

Methods: The Surveillance, Epidemiology, and End Results (SEER) registry database [2004-2011] was queried for cases of unresectable HCC. Patients with missing data and those who received surgery were excluded from the study. A total of 189 patients with unresectable HCC were identified and used for statistical analysis, with 112 receiving SBRT and 77 receiving SIRT. Overall and disease-specific survival was compared using multivariable cox proportional hazard models.

Results: After adjusting for confounding factors (age at diagnosis, gender, race, grade, stage, AFP level and type of surgery), there were no significant difference in overall survival (OS) [hazard ratio (HR), 0.72; 95% confidence interval (CI), 0.49-1.07; P=0.1077] and DSS (HR, 0.70; 95% CI, 0.46-1.05; P=0.0880) for SIRT compared to SBRT. However, patients with elevated AFP level were associated with higher death risk (P=0.0459) and disease specific death risk (P=0.0233) than those with AFP within normal limits in both treatment groups.

Conclusions: The retrospective analysis serves as the first comparison of SIRT to SBRT in treatment of unresectable HCC. Our findings suggest both treatment approaches result in similar outcomes in overall and disease-specific survival benefit. Future prospective randomized trials are needed to better evaluate and compare the two radiation modalities, as well as other non-operative therapies used in the treatment of HCC.

Keywords: Hepatocellular carcinoma (HCC); stereotactic body radiotherapy (SBRT); yttrium radioisotopes.

Figure 1

Kaplan-Meier curves for patients with hepatocellular carcinoma. (A) Overall survival of patients treated with SBRT versus SIRT; (B) disease-specific survival of patients treated with SBRT versus SIRT. SBRT, stereotactic body radiotherapy; SIRT, selective internal radiotherapy.

Figure 2

Forest plot for overall survival.

Figure 3

Forest plot for disease-specific survival.