Main Session
Sep
30
PQA 08 - Gastrointestinal Cancer, Nonmalignant Disease, Palliative Care
3443 - Dose-Volume Constraints Associated with Liver Toxicity in Patients with Small Livers Receiving Liver Stereotactic Body Radiation Therapy
Presenter(s)
Eric Hsu, MD, PhD - Stanford Health Care, Stanford, CA
E. J. Hsu1, S. Richter1, X. Ye1, E. Rahimy1, L. Vitzthum2, D. T. Chang1,3, and E. L. Pollom1; 1Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 2Stanford University School of Medicine, Stanford, CA, 3Department of Radiation Oncology, University of Michigan, Ann Arbor, MI
Purpose/Objective(s):
Stereotactic body radiation therapy (SBRT) is an effective treatment for liver tumors. However, many patients with liver cancer have underlying liver dysfunction, have received prior liver-directed therapies and may be at higher risk for toxicity due to reduced total functioning liver volume. Volumetric liver SBRT dose constraints require sparing at least 700 cc uninvolved liver to minimize radiation-induced toxicity. For patients with smaller liver volumes, especially those with liver volumes < 700 cc, we sought to evaluate the safety of liver SBRT as well as establish additional dose constraints for those who may not be able to meet the 700 cc constraint.Materials/Methods:
We identified patients with liver volume < 1050 cc who received SBRT for liver malignancies in our department. Patients were considered to have liver toxicity if their albumin bilirubin (ALBI) score worsened to grade 3 within 6 months of SBRT. Fisher’s tests, multivariable logistic regression, and Cox proportional hazards tests were used to evaluate the association between various liver dose constraints and incidence of liver toxicity or time to grade 3 ALBI. Bonferroni adjustment was performed to correct for multiple testing.Results:
From 2011 to 2024, we identified 49 patients with primary liver cancer (57%) or liver metastases (43%) treated to a median total dose of 42 Gy (3-5 fractions). Median liver volume was 917 cc (556-1049 cc) and median age was 77 years (35-95). Thirty patients (61%) had received prior resection, TACE, ablation, and/or y90. None received prior SBRT. Twelve patients (25%) experienced liver toxicity following SBRT. The 700 cc being spared from > 21 Gy constraint was not associated with liver toxicity (Odds Ratio [OR] 3.0, 95% 0.2 to 31.3, P=.27). More patients who failed to meet the dose constraint of 550 cc spared from receiving 7 Gy had liver toxicity compared to those who did not (57% vs 11%, OR 1.7, 95% CI 1.3 to 2.2, P=.0004). This dose constraint was also found to be significantly associated with time to grade 3 ALBI (Hazard Ratio 4.4, 95% CI 1.6 to 12.2, P=.005). Other literature-established dose constraints, such as mean liver dose, were not associated with liver toxicity.Conclusion:
In patients with small livers receiving liver SBRT, V700 cc constraints and liver mean dose were not associated with liver toxicity. However, over half of the patients who failed to meet a dose-volume constraint of 550 cc of uninvolved liver being spared from receiving > 7 Gy experienced liver toxicity. Tailoring liver constraints for patients with small livers may help preserve liver function and improve patient outcomes.