Y-90 With MIRD Dosimetry Shows Promise for Intrahepatic Cholangiocarcinoma

AUSTIN, TX—Transarterial Y-90 radioembolization with resin microspheres using MIRD dosimetry for intrahepatic cholangiocarcinoma appears to be safe and shows promising survival outcomes, researchers from Beth Israel Deaconess Medical Center reported in an abstract presented at SIR.

“There is this concept out there that perhaps hotter is better, or more radiation is better,” said lead author Ammar Sarwar, MD. To better understand whether that concept holds true, the researchers investigated the efficacy and safety of transarterial yttrium-90 resin microsphere radioembolization using the Medical Internal Radiation Dosimetry (MIRD) model in patients with intrahepatic cholangiocarcinoma (ICC).

The study was a retrospective review that took place at a single center from April 2015 to April 2018 and evaluated data from 22 consecutive patients who underwent resin Y90. Patients had an average age of 69 years, and 60% were male. Seven patients had extrahepatic disease.

Tumor size was 7 cm, with a range of 3.2 to 13 cm. The distance from a potential resection margin was less than 1 cm. Regarding tumor staging, there were 10 T1A or T1B tumors with normal metastases. One patient had portal vein invasion and normal metastases, and 5 patients had distant metastases.

Resin MIRD Y-90 treatment was provided as a first-line treatment to 82% of patients (14 patients), with 12% receiving chemotherapy before Y-90 (2 patients) and 6% (1 patient) receiving microwave ablation prior to Y-90. The target vessels were the right or left hepatic artery in 61% of patients and segmental branch infusions in 39% of patients.

The target volume for dosimetry on average was 529 cc, while the target dose range was 120 to 200 Gy, with an average dose of 145 Gy. “This was the target absorbed dose, not the actual received dose,” Dr. Sarwar noted. The prescribed activity was approximately 48 mCi and ranged from 8 to 121 mCi. “There were three cases that were recently done with the newer version of the SIR spheres, which was the A+ dose and the A++ dose to get some of the higher activities,” he said.

In all cases, the prescribed activity of 8.1 to 120.7 mCi was successfully delivered (90-108% of prescribed dose). Approximately 20% of patients experienced grade 3 CTCAE v5.0 adverse events. Subsequent therapies included portal vein embolization (1 patient), second Y-90 treatment (2 patients), liver tumor resection (8 patients), radiotherapy for metastatic disease (1 patient), and chemotherapy (6 patients).

The average follow-up is currently 20 months, and 65% of patients were alive at the most recent follow-up. “There are three patients with active disease, two with extrahepatic disease at the time of diagnosis, and one patient who has refused further therapy,” said Dr. Sarwar.

Although the study is limited by the small sample size, single center, and retrospective design, the authors believe the results show promise. Dr. Sarwar and colleagues concluded that “MIRD dosimetry with resin microspheres is feasible and Y-90 may be used as first-line therapy for unresectable liver-only disease.” They added that there was a “high rate of downstaging borderline resectable patients to surgery,” and “good survival outcomes for patients with ICC.”

—Lauren LeBano

Reference

Ahmed M, Bullock A, Faintuch S, et al. Outcomes for borderline resectable intra-hepatic cholangiocarcinoma treated with resin yttrium-90 radioembolization using MIRD model dosimetry. Abstract 233. Presented March 25, 2019. Society of Interventional Radiology Meeting. Austin, Texas.