Caren van Roekel

145 Mode of progression after radioembolization in colorectal cancer patients Of the 90 patients, no patients showed CR, 5 (5.5%) patients had PR, 16 (17.8%) had SD and 69 (76.7%) had PD. According to RECIST, progressive disease can be based on growth of intrahepatic metastases, growth of extrahepatic metastases or new metastases (either intra- or extrahepatic). Growth of intrahepatic metastases was observed in 20 patients (29%), new intrahepatic metastases in 35 patients (51%), growth of extrahepatic metastases in 37 patients (54%), and 56 patients (81%) were diagnosed with new extrahepatic metastases. Most, 67/69 of the progressive patients (97%), had new (intra- hepatic N=11, extrahepatic N=32; or both N=24) metastases. Progression was most often seen on multiple levels (N=42, 61%) and was only based on growth of existing metastases in 5 patients (7%, intra-hepatic N=2, extrahepatic N=3) and on only new lesions in 23 patients (69%) (Figure 2a). In the subgroup of progressive patients with extrahepatic disease at baseline, new extrahepatic metastases were most common, in 28/42 (67%) patients (Figure 2b). There was no significant difference in response between the three types of microspheres used: compared to 90 Y resin microspheres, the odds ratios for progressive disease with 90 Y glass and 166 Ho were 1.11 (95%CI 0.32-4.53) and 0.67 (95%CI 0.22-2.14), respectively (Table 2). 5