PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s): Intrahepatic cholangiocarcinoma (ICC) is a disease of high mortality characterized by aggressive, local infiltration. Surgery is the only curative treatment, but is only an option for a small proportion of patients. For patients unable to receive surgery, there is no established standard treatment, although several options exist, including chemotherapy, conventional external beam radiation therapy (EBRT), stereotactic body radiation therapy (SBRT), chemoradiation, ablation, transarterial chemoembolization (TACE), and transarterial radioembolization (TARE), namely in the form of yttrium-90 (Y-90) microspheres. We studied the overall survival (OS) of patients with ICC treated with primary SBRT vs TARE.
Materials/Methods: We identified 18,344 patients diagnosed between 2005 and 2015 with histologically confirmed ICC using the National Cancer Database (NCDB). We included only patients age ≤85 with a Charlson-Deyo comorbidity score (CDCS) ≤2 (n=14,212). We limited our analysis to patients without nodal or distant metastasis (n=5,006). After excluding patients who received other locoregional treatment modalities or systemic monotherapy, we identified 129 patients who received either primary TARE or SBRT, defined as EBRT to a dose of ≥30 Gy in ≤5 fractions. Chi square test and t-test were used to compare clinical characteristics between treatment cohorts. Univariate log-rank test and cox multiple regression were used for statistical analysis to test the association of covariates with survival.
Results: The SBRT cohort was characterized by older age (mean 71 vs 65, p=.007) and more recent diagnosis (p=.005). There was no difference between the treatment cohorts with regard to T-stage (p=.21), CDCS (p=.58), or use of chemotherapy (p=.20). When only patients with available tumor size were analyzed (n=109), the TARE cohort was characterized by larger tumors (mean 74 vs 47 mm, p<.001). Univariate log-rank testing showed improved OS with SBRT over Y-90, with a median OS of 24.2 months vs 19.8 months (p=0.016). On multivariate analysis, treatment with SBRT was associated with improved OS (HR=0.40, 95% CI .21-.77, p=.006). In contrast, age (p=.11), year of diagnosis (p=.87), tumor size (p=.61), T-stage (p=.11), CDCS (p=.50), or chemotherapy (p=.39) were not significantly associated with OS. When the analysis was limited to patients with known tumor size, treatment modality remained the only statistically significant variable associated with OS.
Conclusion: SBRT is associated with higher OS when compared to TARE in the treatment of unresectable ICC, independent of other variables including tumor size and stage. However, these results should be interpreted cautiously given the retrospective nature of the data and the inherent limitations of the NCDB. Further validation of these findings using other datasets or, potentially, a prospective study is required.
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