Treatment outcomes for unresectable intrahepatic cholangiocarcinoma: Nationwide, population-based, cohort study based on propensity score matching with the Mahalanobis metric

Abstract Purpose No prospective randomized trials have been conducted to date to evaluate the efficacy of palliation of pain or jaundice without treatment, definitive concurrent chemoradiotherapy (CCRT), sequential chemotherapy and radiotherapy (CTRT), or chemotherapy (CT) alone for treating unresectable intrahepatic cholangiocarcinoma (ICC). We designed a nationwide, population-based, cohort study to determine the effects of different treatments on patients with unresectable ICC using propensity score matching (PSM) with the Mahalanobis metric. Patients and methods We classified patients with unresectable ICC from the Taiwan Cancer Registry database into the following 4 treatment groups: group 1, definitive CCRT; group 2, sequential CTRT; group 3, no treatment (palliative therapy for relief of pain, pruritus, or jaundice); and group 4, CT alone. Confounding factors among the 4 treatment groups were minimized through propensity score matching (PSM). Results After PSM, the final cohort consisted of 844 patients (211 patients in each of the 4 groups). In both univariable and multivariable Cox regression analyses, adjusted hazard ratios (aHRs; 95% confidence interval [CI]) derived for groups 1 and 2 compared with group 4 were 0.65 (0.59–0.71) and 0.95 (0.83–1.48), respectively. Furthermore, an aHR (95% CI) of 2.25 (1.89–2.67) was derived for significant independent prognostic risk factors for poor overall survival for group 3 compared with group 4. Conclusions Definitive CCRT is the optimal therapy for patients with unresectable ICC without distant metastasis.