The Impact of Dose on Overall Survival in Unresectable Hepatocellular Carcinoma Treated With Stereotactic Body Radiation Therapy International Journal of Radiation Oncology, Biology, Physics POSTER VIEWING ABSTRACT| VOLUME 96, ISSUE 2, SUPPLEMENT , E152, OCTOBER 01, 2016
Date
10/01/2016Abstract
Purpose/Objective(s)
The utilization of stereotactic body radiation therapy (SBRT) for unresectable hepatocellular carcinoma (HCC) is increasing, but there remains little evidence about the optimal dose scheme and the effects of dose on overall survival (OS). We examine the effects of radiation dose as measured by the biological equivalent dose (BED) in a cohort of HCC patients identified in a large national database.
Materials/Methods
Patients with unresectable, non-metastatic HCC that received SBRT were identified from the National Cancer Database (2004-2013). Survival outcomes were compared using Kaplan Meier curves and log-rank tests, and multivariate Cox (MVC) proportional hazards model to examine the predictors of survival. BED was calculated for each patient using the delivered dose, number of fractions, and an α/β ratio of 10.
Results
A total of 461 patients met the inclusion criteria. Median patient age and tumor size were 62 years (27-90) and 3.2 cm (0.6-17), respectively. Charlson comorbidity index score was 0 in 61%, 1 in 20%, and ≥2 in 19%. By stage 56% were stage I, 29% were stage II, and 15% were stage III. Alpha-fetoprotein (AFP) was elevated in 52.9%, and 32% received chemotherapy. The median BED was 100 Gy (22.5-208.0), which was also the most common dose fractionation (50 Gy in 5 fractions) in 21.7%. Other common scheme included: 40 Gy in 5 fractions (BED of 72 Gy) in 14.8%, 48 Gy in 3 fractions (BED of 124 Gy) in 10.7%, and 45 Gy in 3 fractions (BED of 112.5 Gy) in 6.7%. For this entire cohort, the median OS after SBRT was 20.3 months. An apparent dose response was observed with improved survival with increasing BED. The median and 1-year OS were 15.3 months and 56.6% for BED≤75, 18.3 months and 67.5% for BED>75 and ≤100, and 37.2 months and 81.4% for BED>100, P< 0.001. When controlling for other factors (tumor size, AFP, stage, comorbidity level, age, type of institution and type of insurance), an increased BED was associated with longer OS regardless of how BED was analyzed (see table 1). In addition, elevated AFP (HR 1.803, 95% CI 1.235-2.632, P = 0.002) and increased tumor size (HR 1.085, 95% CI 1.023-1.150, P = 0.006) were associated with worse survival.
Conclusion
In this sizable cohort of HCC patients treated with SBRT, those who received higher BED appear to have improved OS, even when controlling for multiple other factors. While many factors influence the determination of dose for any given patient, this data may suggests that efforts to safely increase BED may result in improved survival outcomes. This concept, as well as strategies, to achieve it should be investigated in prospective clinical trials.
Author List
A.Y. Hammad R.K. Schmid B.A. Erickson T.C. Gamblin J.R. RobbinsAuthor
Beth A. Erickson MD Professor in the Radiation Oncology department at Medical College of WisconsinView Online
