Personalized dosimetry enhances hepatocellular carcinoma response in Yttrium-90 resin microsphere radioembolization

OBJECTIVES: To identify a tumor-mean absorbed dose (Dmean) that can predict response to Yttrium-90 resin-microsphere transarterial radioembolization (TARE) in patients with hepatocellular carcinoma (HCC) and evaluate its efficacy and safety. MATERIALS AND METHODS: Patients with HCC eligible for TARE in two centers between January 2020 and May 2024 were retrospectively analyzed. Clinical, radiological, and procedural data were collected. Objective response rate (ORR) on lesion, complete response (CR), overall response, time-to-local progression (TLP), and time-to-progression (TTP) were evaluated on contrast-enhanced CT at 3 and 6 months according to mRECIST. The optimal Dmean of ORR on the target lesion and of CR was identified with ROC analysis at 3-months. Fischer's test compared ORR, Kaplan-Meier survival outcomes, and Cox regression was used for uni-and multivariable analyses. RESULTS: Seventy-six lesions in 64 patients (mean age 71.3 ± 9.6; 54 men) were evaluated. Median follow-up was 15.0 months (IQR 8.0-24.3). Mean tumor diameter was 55.2 (± 31.8) mm. CR on target lesion at 3-months was achieved in 42 lesions. Mean TLP and OS were 27.6 ± 2.5 and 36.2 ± 2.9 months, respectively. The calculated Dmean for ORR was 296.74 Gy (specificity 100, PPV 100%). Patients treated with equal or lower doses had a significantly shorter TLP (log-rank p = 0.001). Dmean > 296.74 Gy did not increase the risk of complications. A Dmean > 435.11 Gy predicts CR. CONCLUSION: A Dmean threshold of 296.74 Gy provides significant therapeutic efficacy without compromising patient safety. All HCC lesions treated with > 435.11 Gy achieved CR. KEY POINTS: Question In patients with HCC treated with 90Y-resin microsphere TARE, can an optimized personalized dose improve efficacy without compromising safety? Findings The calculated mean dose (Dmean), even though above guideline indications, did not yield serious adverse events whilst enhancing response to treatment. Clinical relevance HCC recurrence is associated with poor patient outcomes. Personalized dosimetry is best practice for tailoring radioactive doses, and the cut-off dose calculated in this cohort identifies that with the best response and yields additional data on resin microsphere doses.