DEFINING THE ROLE OF ADJUVANT RADIOTHERAPY FOR BILE DUCT CANCERS: A SITE-SPECIFIC PROPENSITY-MATCHED ANALYSIS
Andrew D. Newton*, Yi-Ju Chiang, Timothy E. Newhook, Ching-Wei D. Tzeng, Yun Shin Chun, Ethan B. Ludmir, Eugene Koay, Milind Javle, Jean-Nicolas Vauthey, Hop Tran Cao
Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Introduction: The benefit of adjuvant radiation for resected bile duct cancers is unknown.
Methods: Patients with resected intrahepatic (IHC), perihilar (PHC) and distal cholangiocarcinoma (DCC), and gallbladder cancer (GBC) were identified in the National Cancer Database (2004-2017). Patients who died within 90 days of surgery or with R2 resections were excluded. For each disease site, patients were propensity-matched 1:1 on predictors of adjuvant radiation identified by logistic regression.
Overall survival (OS) with no adjuvant treatment, adjuvant chemotherapy alone, or adjuvant radiation ± chemotherapy was compared by Kaplan-Meier estimates. Following multivariable logistic regression, the association of treatment strategy with OS stratified by margin and lymph node status was compared.
Results: There were 22,722 patients in the entire cohort and 8,478 propensity-matched patients (n=1,548 IHC, n=1,334 PHC, n=1,568 DCC, n=4,028 GBC). In propensity-matched patients, median OS with adjuvant radiation vs. no adjuvant treatment was: IHC: 32.8 vs. 36.9 months, p=0.55; PHC: 31.8 vs. 27.3 months, p=0.12; DCC: 32.4 vs. 26.9 months, p=0.008; and GBC: 28.0 vs. 23.0 months, p<0.001. Median OS with adjuvant radiation vs. chemotherapy alone was: IHC: 33.1 vs. 32.0 months, p=0.25; PHC: 31.4 vs. 31.7 months, p=0.86; DCC: 34.2 vs. 27.5 months, p=0.003; and GBC: 27.0 vs. 18.2 months, p<0.001. The association of adjuvant treatment with OS stratified by margin and lymph node status is shown in Figure 1.
Conclusions: Adjuvant radiation is associated with improved OS for DCC, GBC, and when compared to no adjuvant therapy, PHC, but not IHC. This should be studied further in randomized trials.
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