Adjuvant Radiotherapy for Extrahepatic Cholangiocarcinoma: A Quality Assessment-Based Meta-Analysis

Introduction: The benefits of adjuvant radiotherapy (ART) for extrahepatic cholangiocarcinoma are uncertain largely because existing publications lack clear comparisons between ART and non-ART arms. Methods: PubMed, Medline, Embase, and the Cochrane library were systematically searched until December 2020. The primary endpoint was overall survival (OS). Sensitivity analysis was performed for studies with reliable comparability (i.e., no favorable prognosticators in the ART arm that could skew the data). Results: Twenty-three studies involving 1,731 patients with extrahepatic cholangiocarcinoma were reviewed. The overall median of all median prescribed doses was 50.4 Gy; brachytherapy or an intraoperative boost of 10-21 Gy was applied in 5 studies. The pooled 1-, 3-, and 5-year OS rates in the non-ART and ART arms were 69.2% versus 81.0%, p = 0.035; 34.3% versus 44.7%, p = 0.025; 25.6% versus 31.7%, p = 0.115, respectively. The corresponding pooled locoregional recurrence rates were 52.1% versus 34.9% (p = 0.014). The pooled rate of grade ≥3 gastrointestinal complications was 9.8%. Sensitivity analysis performed on 14 eligible studies showed that the ART arms had a lower pooled R0 rate (36.8% vs. 63.2%, p = 0.02) and a higher rate of positive lymph nodes (47.4% vs. 34.9%, p = 0.08). The pooled 1-, 3-, and 5-year OS rates in the non-ART versus ART arms of the selected studies were 78.2% versus 84.9%, p = 0.143; 38.5% versus 49.2%, p = 0.026; and 27.8% versus 34.5%, p = 0.11, respectively. Conclusions: ART was shown to improve OS in all studies and in those selected for their reliable comparability.