Improving patient selection for selective internal radiation therapy of intra-hepatic cholangiocarcinoma: A meta-regression study

Background & Aims: Selective internal radiation therapy (SIRT) is emerging as a potential therapy for unresectable intra-hepatic cholangiocarcinoma (iCCA) able to prolong life-expectancy. Aim of this study was to collect available literature meta-analyse data and results and investigate sources of heterogeneity through a meta-regression approach before suggesting SIRT as a valuable option. Methods: A systematic review of studies published until 1 September 2016 in PubMed and Scopus databases was performed. Patient survival was the primary outcome measure. Meta-analysis was performed using a random-effects model. Meta-regression was applied to investigate relationships existing between clinical and tumour features and the primary outcome. Results: Nine observational studies were included in the analysis involving 224 patients. The 1-, 2- and 3-year pooled survival estimates were 55.7%, 33.1% and 20.2%. Clinical and tumour characteristics showed medium-to-considerable heterogeneity (I2>50%). Meta-regression analysis showed that determinants of best survivals were the presence of mass-forming iCCA type (median survival=19.9 months vs 8.1 months for the infiltrative type; P=.002) that also accounted for most of the heterogeneity between included studies (residual I2=0); SIRT as first-line therapy (median survival=24 months vs 11.5 months for non-naïve patients; P=.048) and the adoption of concomitant chemotherapy (median survival 19.5 months vs 5.5 months in patients not receiving chemotherapy; P=.042). Conclusions: There is considerable heterogeneity between studies highlighting that indications for SIRT are extremely varied. To ameliorate SIRT results naïve patients with mass-forming iCCA should be selected as the best candidates with the possibility of adding concomitant standard chemotherapy.