CIO 2023-33 Tumor Size and Watershed Area Correlates in Progression of Hepatocellular Carcinoma after Segmental Radioembolization

Purpose: To identify factors of incomplete treatment after segmental transarterial radioembolization (TARE) for treatment-naïve and solitary hepatocellular carcinoma (HCC)

Material and Methods: A total of 75 consecutive patients (age 68.5 ±8.0 years, 25/75 [33.3%] female) with treatment-naive, solitary HCC underwent segmental TARE with glass microspheres (tumor size 3.8 ± 2.2 cm, target dose 222.6 ± 123.9 Gy) at a single institution. Radiologic response and progression-free survival (PFS) were assessed per modified Response Evaluation Criteria in Solid Tumors.

Results: Complete treatment was achieved in 48/75 (64.0%) patients (mean follow-up 33.2 ± 27.4 months). Patients with incomplete treatment (27/75, 36%) had larger tumor size (5.0 cm vs 3.1 cm p=0.0001) with more tumors located in the watershed zone (81.5 vs 41.7% p=0.001). These patients were less likely to be bridged to transplant or resection (22.2% vs 52.1% p=0.015). No significant difference was observed regarding age, sex, Child-Pugh Score, Model for End-Stage Liver Disease (MELD)/Na-MELD Score, albumin-bilirubin score/grade, Eastern Cooperative Oncology Group performance, liver disease etiology, and target dose. Watershed tumors demonstrated early target tumor PFS (p=0.0104), de novo hepatic PFS (p=0.0225), and overall PFS (p=0.0077). Watershed location was associated with worse PFS among tumors > 3cm (p=0.035) but not tumors ≤ 3cm (p=0.915).

Conclusions: Tumor size and watershed location were associated with incomplete response after segmental TARE for HCC. Watershed tumors were associated with worse PFS, particularly tumors larger than 3 cm. These tumors may require careful treatment planning and repeated treatments to ensure a durable response.