A MAA-based dosimetric study in patients with intrahepatic cholangiocarcinoma treated with a combination of chemotherapy and Y-loaded glass microsphere selective internal radiation therapy.

Purpose: Selective internal radiation therapy (SIRT) appears to be an interesting treatment possibility for locally-advanced intrahepatic cholangiocarcinoma (ICC), yet the appropriate dosimetry has never been evaluated in this context.

Methods: We retrospectively studied data from 40 patients treated at our institution with Y-loaded glass microsphere SIRT combined with chemotherapy for inoperable ICC as first-line treatment. Macroaggregated albumin (MAA)-based single-photon emission computed tomography (SPECT)/computed tomography (CT) quantitative analysis was used to calculate the tumor dose (TD), healthy-injected liver dose (HILD), and injected liver dose (ILD). Response was evaluated at 3 months using the European Association for the Study of the Liver criteria. Factors associated with response and toxicity were analyzed using univariate analysis.

Results: We assessed a total of 35 patients (five excluded) receiving 55 injections. Mean TD was 322 ± 165Gy and mean HILD was 74 ± 24Gy for a mean ILD of 128 ± 28Gy. All but two lesions responded, with a minimal TD for responding lesions of 158Gy. Six Grade 3-4 permanent liver toxicities were observed. Mean HILD was not associated with liver toxicity (73.2 ± 25.8Gy for patients with liver toxicity and 77.8 ± 16.9Gy for patients without, ns). Only underlying Child-Pugh status (p = 0.0014) and underlying cirrhosis (p = 0.0021) were associated with liver toxicity. Median progression-free survival was 12.7 months and median overall survival (OS) was 28.6 months. Median OS was 52.7 months for patients with Child-Pugh A5 status.

Conclusions: When combined with chemotherapy, SIRT is highly effective, with a TD > 158Gy. Tolerance was good except for the few patients with cirrhosis or Child-Pugh status ≥A6, who exhibited some liver toxicity. Prospective studies are warranted to confirm.