Role of Stereotactic Body Radiation Therapy Before Orthotopic Liver Transplantation: Retrospective Evaluation of Pathologic Response and Outcomes.

PURPOSE: To analyze the results of stereotactic body radiation therapy (SBRT) in patients with early-stage, localized hepatocellular carcinoma who underwent definitive orthotopic liver transplantation (OLT). METHODS AND MATERIALS: The subjects of this retrospective report are 38 patients diagnosed with hepatocellular carcinoma who underwent SBRT per institutional phase 1 to 2 eligibility criteria, before definitive OLT. Pre-OLT radiographs were compared with pathologic gold standard. Analysis of treatment failures and deaths was undertaken. RESULTS: With median follow-up of 4.8 years from OLT, 9 of 38 patients (24%) recurred, whereas 10 of 38 patients (26%) died. Kaplan-Meier estimates of 3-year overall survival and disease-free survival are 77% and 74%, respectively. Sum longest dimension of tumors was significantly associated with disease-free survival (hazard ratio 1.93, P=.026). Pathologic response rate (complete plus partial response) was 68%. Radiographic scoring criteria performed poorly; modified Response Evaluation Criteria in Solid Tumors produced highest concordance (κ = 0.224). Explants revealed viable tumor in 74% of evaluable patients. Treatment failures had statistically larger sum longest dimension of tumors (4.0 cm vs 2.8 cm, P=.014) and non-statistically significant higher rates of lymphovascular space invasion (44% vs 17%), cT2 disease (44% vs 21%), ≥pT2 disease (67% vs 34%), multifocal tumors at time of SBRT (44% vs 21%), and less robust mean α-fetoprotein response (-25 IU/mL vs -162 IU/mL). CONCLUSIONS: Stereotactic body radiation therapy before to OLT is a well-tolerated treatment providing 68% pathologic response, though 74% of explants ultimately contained viable tumor. Radiographic response criteria poorly approximate pathology. Our data suggest further stratification of patients according to initial disease burden and treatment response.

Treatment variables related to liver toxicity in patients with hepatocellular carcinoma, Child-Pugh class A and B enrolled in a phase 1-2 trial of stereotactic body radiation therapy.

PURPOSE: An analysis was performed on patients enrolled in a phase 1-2 trial using stereotactic body radiation therapy for hepatocellular carcinoma evaluating variables influencing liver toxicity. METHODS AND MATERIALS: Thirty-eight Child-Pugh class A (CPC-A) (39 lesions) and 21 CPC-B patients (26 lesions) were followed for ≥6 months. Six months local control using modified Response Evaluation Criteria in Solid Tumors criteria, progression-free survival, overall survival, and grade III/IV treatment-related toxicity at 3 months were analyzed. RESULTS: Median follow-up was 33.3 months (2.8-61.1 months) for CPC-A and 46.3 months (3.7-70.4 months) for CPC-B patients. Local control at 6 months was 92% for CPC-A and 93% for CPC-B. Kaplan-Meier estimated 2- and 3-year local control was 91% for CPC-A and 82% for CPC-B (P = .61). Median overall survival was 44.8 months and 17.0 months for CPC-A and CPC-B. Kaplan-Meier estimated 2- and 3-year overall survival was 72% and 61% for CPC-A and 33% and 26% for CPC-B (P = .03). Four (11%) CPC-A patients and 8 CPC-B patients (38%) experienced grade III/IV liver toxicity. Overall, CPC-A patients with ≥grade III liver toxicity had 4.59 (95% confidence interval, 1.19-17.66) times greater risk of death than those without toxicity (P = .0268). No such correlation was seen for CPC-B patients; however, 3 of these CPC-B patients underwent orthotopic liver transplant. CPC-B patients experiencing grade III/IV liver toxicity had significantly higher mean liver dose, higher dose to one-third normal liver, and larger volumes of liver receiving doses <2.5 to 15 Gy in 2.5-Gy increments. For CPC-A patients, there was no critical liver dose or volume constraint correlated with toxicity. CONCLUSIONS: In our experience, liver stereotactic body radiation therapy is a safe therapy for patients with hepatocellular carcinoma in the context of liver cirrhosis; however, for CPC-B patients, careful attention should be paid to low-dose volumes that could potentially result in increased liver toxicity.

Evaluation of rotational errors in treatment setup of stereotactic body radiation therapy of liver cancer.

PURPOSE: To evaluate the dosimetric impact of rotational setup errors in stereotactic body radiotherapy (SBRT) treatment of liver tumors and to investigate whether translational shifts can compensate for rotation. METHODS AND MATERIALS: The positioning accuracy in 20 patients with liver malignancies treated with SBRT was reevaluated offline by matching the patients' cone-beam computed tomography (CT) scans (n=75) to the planning CT scans and adjusting the 3 rotational angles (pitch, roll, and yaw). Systematic and random setup errors were calculated. The dosimetric changes caused by rotational setup errors were quantified for both simulated and observed patient rotations. Dose distributions recalculated on the rotated CT scans were compared with the original planned doses. Translational corrections were simulated based on manual translational registration of the rotated images to the original CT scans. The correction efficacy was evaluated by comparing the recalculated plans with the original plans. RESULTS: The systematic rotational setup errors were -0.06° ± 0.68°, -0.29° ± 0.62°, and -0.24° ± 0.61°; the random setup errors were 0.80°, 1.05°, and 0.61° for pitch, roll, and yaw, respectively. Analysis of CBCT images showed that 56.0%, 14.7%, and 1.3% of treated fractions had rotational errors of >1°, >2°, and >3°, respectively, in any one of the rotational axes. Rotational simulations demonstrated that the reduction of gross tumor volume (GTV) coverage was <2% when rotation was <3°. Recalculated plans using actual patient roll motions showed similar reduction (<2%) in GTV coverage. Translational corrections improved the GTV coverage to within 3% of the original values. For organs at risk (OAR), the dosimetric impact varied case by case. CONCLUSION: Actual rotational setup errors in SBRT for liver tumors are relatively small in magnitude and are unlikely to affect GTV coverage significantly. Translational corrections can be optimized to compensate for rotational setup errors. However, caution regarding possible dose increases to OAR needs to be exercised.