Co-relation of portal vein tumour thrombus response with survival function following Robotic Radiosurgery in vascular invasive hepatocellular carcinoma

Purpose or Objective Prospective evaluation of stereotactic body radiotherapy (SBRT) with Robotic Radiosurgery in hepatocellular carcinoma patients with macrovascular invasion (HCC-PVT). Materials and Methods Patients with inoperable HCC-PVT, good performance score (PS0-1) and preserved liver function (up to Child Pugh B7) were accrued after ethical and scientific committee approval [CTRI: 2022/01/050234] for treatment on Robotic Radiosurgery (M6) and planned with Multiplan (iDMS V2.0). Triple-phase contrast computed tomography (CT) scan was done for contouring and gross tumor volume (GTV) included contrast enhancing mass within main portal vein and adjacent parenchymal disease. Dose prescription was as per risk stratification protocol (22- 50Gy in 5 fractions) while achieving the constraints of mean liver dose <15Gy, 800 cc liver <8Gy and the duodenum max of <24 Gy). Response assessment done at 2 months follow up for recanalization. Patient and treatment related factors evaluated for influence in survival function. Results Between Jan 2017 till May 2022, 317 consecutive HCC with PVT patients were screened and 219 patients were accrued [male 92%, CP score 5-7 90%, mean age 63 years (38-85yrs), CLIP <3: 84 (40%), 3-6 117 (56%), infective etiology 9.5%, Performance status (PS) 0-37%; 1-56%]. Among 209 consecutive patients after accrual SBRT treatment done (10 patients were excluded after accrual due to ascites and decompensation), 139 were evaluable for response assessment (>2 mo follow up). At mean follow up of 10.2 months (SD 8.43), 88 (63%) patients expired and 51 (36%) were alive. 82 (59%) patients had recanalization of PVT (response), 57 (41%) pts did not recanalize, 28 (17%) had progressive disease had progressive/metastatic disease prior to response evaluation (<2 months). Mean overall survival in responders and non-responders were 18.4 (SE 2.52) and 9.34 month (SE 0.81) respectively (p<0.001). Mean survival in patients with PS0, PS1 and PS2 were 17, 11.7 and 9.7 months (p- 0.019) respectively. Overall survival (OS) in partial recanalization, bland thrombus and complete recanalization was 12.4, 14.1, 30.3 months respectively (p-0.002). Adjuvant sorafenib, Barcelona Clinic Liver Classification (BCLC) stage, gender, age, RT dose did not influence response to treatment. Recanalization rate was higher in good PS patients (p-0.019). OS in patients with response to treatment, no response to treatment, fit but not accrued and not suitable patients were 18.4, 9.34, 5.9, 2.6 months respectively (p-<0.001). 36/139 patients (24%) had RILD [10 (7.2%) had Classic Radiation induced liver disease (RILD) & 26 (19%) had non-classic RILD]. Derangement in Child Pugh Score (CP score change) by more than 2 was seen in 30 (24%) within 2-month period after Robotic Radiosurgery. 18 (13%) had unplanned admissions, two patients required embolization due to fiducial related bleeding, 20 (14%) had ascites of which 9 (6%) patients required abdominocentesis. Conclusion PVT response or recanalization after SBRT is a statistically significant prognostic factor for survival function in HCC-PVT.