Holmium-166 radioembolisation dosimetry in HCC

Area of Science:

• Hepatobiliary Cancers
• Interventional Radiology
• Nuclear Medicine

Background:

• Hepatocellular carcinoma (HCC) is a primary liver cancer with limited treatment options.
• Radioembolisation using holmium-166 (166Ho) microspheres offers a targeted radiation therapy approach.
• Optimizing dosimetry is crucial for maximizing treatment efficacy and minimizing toxicity in HCC radioembolisation.

Purpose of the Study:

• To evaluate the dosimetry, dose-response, and dose-toxicity relationships of 166Ho radioembolisation in HCC patients.
• To establish preliminary absorbed dose thresholds for predicting tumor response.
• To assess the association between non-tumor absorbed dose and treatment-related adverse events.

Main Methods:

• Thirty-one HCC patients underwent 166Ho-microspheres radioembolisation as part of the HEPAR Primary study.
• Linear mixed models analyzed the association between tumor absorbed dose and treatment response (mRECIST).
• Linear regression models examined the relationship between non-tumor absorbed dose and toxicity (CTCAE v4.03).

Main Results:

• Median tumor absorbed dose was 95.5 Gy; median non-tumor absorbed doses were 19 Gy (whole liver) and 30 Gy (target liver).
• A significant association was found between non-tumor absorbed dose and toxicity.
• Tumors achieving partial or complete response received 41% higher absorbed doses than non-responders (p=0.04).
• Tumor absorbed dose thresholds for 90% and 100% response prediction were 155 Gy and 184.5 Gy, respectively.

Conclusions:

• A positive correlation exists between tumor absorbed dose and treatment response in HCC patients.
• Higher non-tumor absorbed doses are associated with increased toxicity.
• Established dose thresholds can guide personalized dosimetry for 166Ho-microspheres radioembolisation in HCC.