Gastrointestinal Cancer

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SU_14_2145 - Value of Functional Liver Imaging in Heavily Pre-Treated Hepatocellular Carcinoma Patients

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Value of Functional Liver Imaging in Heavily Pre-Treated Hepatocellular Carcinoma Patients
S. K. Schaub1, S. R. Bowen1, R. G. Price1, M. Nyflot1, T. R. Chapman2, and S. Apisarnthanarax3; 1University of Washington, Department of Radiation Oncology, Seattle, WA, 2Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 3University of Washington Medical Center Department of Radiation Oncology, Seattle, WA

Purpose/Objective(s): There is an ongoing need for mitigating radiation-induced liver disease (RILD) in hepatocellular carcinoma (HCC), particularly in cirrhotics and heavily pre-treated patients with multiple prior liver-directed therapies (LDTs). We hypothesize that global and spatial functional dosimetry parameters obtained from [99mTc]-sulfur colloid (SC) SPECT/CT imaging could be of significant value in heavily pre-treated HCC patients.

Materials/Methods: We retrospectively reviewed 47 HCC patients treated with low (0-2) vs. high (3+) number of prior LDTs, excluding radiofrequency ablation, who underwent SC SPECT/CT imaging for radiotherapy (RT) planning. From this cohort, we performed a case-matched analysis that controlled for baseline Child-Pugh (CP) class and RT modality. Global functional metrics, including the FLV30 (ratio of the functional liver volume at 30% maximum SC intensity divided by the anatomic liver-GTV volume), and anatomic dosimetry (liver-GTV) were extracted as previously published. Prior LDT subgroup comparisons were performed with Fisher Exact and Chi-square tests for categorical variables, as well as Mann-Whitney tests for continuous variables.

Results: We identified 24 case-matched HCC patients with either low LDTs (n=12) or high LDTs (n=12). Median age was 69 (49-89) with baseline CP-A (87.5%), and CP-B (12.5%). The median follow-up was 602 days (11-1102). RT modality was either SBRT (n=12) or hypofractionated proton RT (n=12). Median number of prior LDTs were 0 (0-2) in the low LDT group and 3.5 (3-8) in the high LDT group. The groups had no difference in underlying tumor or anatomic liver volumes (p>0.356). FLV30 ratio was lower in high LDT (73% of liver-GTV) vs. low LDT (83% of liver-GTV) patients (p=0.050), suggesting larger discrepancies between CT-defined anatomic liver volumes and FLVs in heavily pre-treated patients. The high LDT group had increased SC SPECT heterogeneity as measured by the coefficient of variation (0.46 vs 0.38, p=0.038). Figure 1 illustrates the spatial heterogeneity seen on SC SPECT/CT scans in patients with high LDTs compared to those with low LDTs. Analysis of the entire cohort (n=47) revealed that CP-A patients had a trend towards being more heavily pre-treated compared to C-B/C (p=0.074).

Conclusion: SC SPECT/CT functional liver imaging captures compromised regions of liver function not apparent on CT imaging and may be particularly useful for RT planning in HCC patients who have received multiple catheter-based therapies.

Author Disclosure: S.K. Schaub: None. S.R. Bowen: Research Grant; National Cancer Institute. R.G. Price: None. M. Nyflot: None. T.R. Chapman: None. S. Apisarnthanarax: Honoraria; Medtronic. Consultant; Medtronic.

Stephanie Schaub, MD

University of Washington

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