Room: Stars at Night Ballroom 2-3
Purpose: In the era of precision medicine and personalized radiation treatment (RT), there is an ever-growing need to find predictive biomarkers of treatment response in patients. Here we investigate the potentials of using mid-treatment MR images and inflammatory cytokines as biomarkers of liver toxicity.
Methods: Eleven intrahepatic metastatic patients who had proton stereotactic body radiotherapy (SBRT) to the liver lesion were retrospectively analyzed. Two Gd-EOB-DTPA (a hepatobiliary-directed contrast agent)-enhanced MR scans as well as three inflammatory cytokines (interleukin 6 [IL-6], IL-8, and tumor necrosis factor Î± [TNF- Î±]) were acquired during the RT course. Deformable image registrations were done among mid-treatment (fx4 and 5) MR images and the planning CT. MR signal changes and delivered dose were then calculated for each voxel. Mid-treatment changes in the expression of the cytokines were calculated with respect to the pre-treatment baseline. Liver toxicity was assessed at 3 months post-RT, using Child-Pugh (CP) and ALBI score. Patients were subsequently classified into high-risk (HR) and low-risk (LR) groups. Statistical analysis was performed to compare the changes in the MR signals and cytokine expressions between these groups.
Results: On average, high-risk patients had lower high-dose/low-dose mid-treatment signal changes (i.e., decreased/increased signal in high-dose/low-dose). In CP classification, there was a significant difference in MR signal change between two group means (0.61 and 1.04 for HR and LR groups; p-value=0.005). The ALBI classification showed more pronounced difference (0.61 vs. 1.11, p-value = 0.002). High-risk patients also showed larger IL-6 changes during their treatment (86% vs. 0.33%, p-value=0.01).
Conclusion: Using mid-treatment MR scans and interleukin 6 as biomarkers, it is possible to predict the risk of acute liver toxicity, already during the RT course. This biomarker information can be potentially used for adaptive planning and RT plan personalization.