Is there any effect of hcc location on selective internal radiation therapy with 90yttrium response?

We planned this retrospective study to evaluate the effect of the central vs peripheral location effect on the success of selective internal radiation therapy (SIRT) with 90Yttrium-90 (90Y) glass microspheres in hepatocellular carcinomas (HCC). Thirty-eight patients diagnosed with HCC who were eligible for SIRT with 90Y glass microspheres were included in this study. The location being central versus peripheral was defined as explained: Straight lines through the bifurcation of the right and left branches of the portal vein to the center of the HCC and the peripheral surface of the liver were traced on the same plane. The coefficient was determined as a ratio of the center of the HCC to the distance from the hilum of the liver at the portal vein bifurcation. Value under ½ accepted as central location (Group 1, n = 17), over ½ values are accepted as peripheral location (Group 2, n = 21). Treatment responses were analyzed after 2 months of the treatment with magnetic resonance imaging, and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT) for FDG-avid ones. Differences in treatment responses rates, treatment approach, the absorbed doses and the volumes of each liver segments between groups were investigated. In Group 1; mean age was 67. In 5 cases split infusion, in 10 cases tumor selective treatment approach were applied. According to PERCIST/mRECIST criteria treatment responses categories: complete response in 2/1 cases, partial response in 7/9 cases, stable disease in 3/4 cases, progressive diseases in 2/3 cases; respectively. AFP value decreased in 2 cases, increased in 7 cases, and was stable in 1 case. Mean absorbed doses were 347.9 Gy for tumor, 140.6 Gy for perfused normal tissue, and 26.1 Gy for the normal liver. In Group 2; the mean age was 71.5. In 5 cases split infusion, and in 1 case non-selective treatment approach were applied. According to PERCIST/mRECIST criteria treatment responses categories: complete response in 7/6 cases, partial response in 7/10 cases, stable disease in 2/2 cases, and progressive diseases in 3/3 cases; respectively. AFP value decreased in 9 cases, increased in 2 cases, and was stable in 2 cases. Mean absorbed doses were 495.9 Gy for tumor, 134 Gy for perfused normal tissue, and 17.3 Gy for the normal liver.There is no statistically significant difference in terms of gender, treatment response rates, tumor volumes, perfuse tissue volumes between 2 groups. However, tumor-selective approach and absorbed doses of the perfused normal tissue and the tumor were significantly higher in Group 2 (p = 0.007, 0.04, and 0.02; respectively). Contrary to expectation, centrally located HCCs could be treated as successfully as peripherally located HCCs. However, the complete response rate in the peripheral located tumor is more frequent than centrally located ones.