Caren van Roekel

136 Chapter 5 ABSTRACT Background Radioembolization is an established treatment modality in colorectal cancer patients with liver-dominant disease in a salvage setting. Selection of patients who will benefit most is of vital importance. The aim of this study was to assess response (and mode of progression) at three months after radioembolization and the impact of baseline characteristics. Methods Three months after radioembolization with either yttrium-90 resin/glass or holmium-166, anatomic response, according to RECIST 1.1, was evaluated in 90 patients. Correlations between baseline characteristics and efficacy were evaluated. For more detailed analysis of progressive disease as a dismal clinical entity, distinction was made between intra- and extrahepatic progression, and between progression of existing metastases and new metastases. Results Forty-two patients (47%) had extrahepatic disease (up to five ≥1 cm lung nodules, and ≤2 cm lymph nodes) at baseline. No patients showed complete response, 5 (5.5%) patients had partial response, 16 (17.8%) stable disease and 69 (76.7%) progressive disease. Most progressive patients (67/69; 97%) had newmetastases (intra-hepatic N=11, extrahepatic N=32; or both N=24). Significantly fewer patients had progressive disease in the group of patients presenting without extrahepatic metastases at baseline (63% versus 93%; p=0.0016). Median overall survival in patients with extrahepatic disease was 6.5 months, versus 10 months in patients without extrahepatic disease at baseline (hazard ratio 1.79, 95%CI 1.24-2.57. Conclusions Response at three-month follow-up and survival were heavily influenced by new metastases. Patients with extrahepatic disease at baseline had a worse outcome compared to patients without. Keywords Metastatic Colorectal Cancer, Radioembolization, Progression, RECIST, Extrahepatic Metastases