Radiation segmentectomy: a novel approach to increase safety and efficacy of radioembolization.

PURPOSE: To describe a technique of segmental radioembolization for the treatment of patients with unresectable hepatocellular carcinoma (HCC). Radiation segmentectomy was defined as radioembolization of two or fewer hepatic segments. We sought to (1) calculate dose when activity is delivered segmentally assuming uniform and nonuniform distribution and, (2) determine safety and efficacy of this novel technique. METHODS AND MATERIALS: A total of 84 patients with HCC who were treated with (90)Y radioembolization using a segmental approach were included in this analysis. The dose delivered to the segment was calculated assuming uniform and nonuniform microsphere distribution within the treatment volume. To calculate dose assuming nonuniform distribution, a tumor hypervascularity ratio was assigned. Posttreatment response (using size and necrosis guidelines), toxicity, time to progression, and survival were determined.
RESULTS: The median treatment volume was 110 cm(3). The median radiation-naïve liver volume was 1403 cm(3). The median dose delivered to the segment(s) assuming uniform distribution was 521 Gy. Taking into account tumor hypervascularity (nonuniform distribution), the median dose delivered to the tumor and normal infused hepatic volume was 1214 Gy and 210 Gy, respectively. Response by size and necrosis guidelines was seen in 59% and 81% of patients. Grade 3/4 biochemical toxicities were observed in 8 patients (9%). Median time to progression was 13.6 months (95% confidence interval, 9.3-18.7 months); median survival was 26.9 months (95% confidence interval, 20.5-30.2 months).
CONCLUSIONS: Radiation segmentectomy is a safe and efficacious method of selectively delivering high dose to the tumor with minimal exposure of normal parenchyma.