Impact of chemotherapy and external beam radiation therapy on outcomes among patients with resected gallbladder cancer: A multi-institutional analysis.

Abstract

387 Background: Use of adjuvant chemotherapy (CTx) and chemoradiation therapy (cXRT) in the treatment of resectable gallbladder cancer remains varied. We sought to define the utilization and effect of adjuvant therapy on patients having undergone curative-intent resection for gallbladder cancer. Methods: Using a multi-institutional national database, 291 patients with gallbladder cancer who underwent curative-intent resection between 2000 and 2015. Patients with metastasis or an R2 margin were excluded. The impact of adjuvant therapy on survival was analyzed among patients who received surgery alone versus CTx versus cXRT. Results: Median patient age was 66 years. Most patients had a T2 (41.9%) or T3 (35.1%) lesion and 37.8% of patients had lymph node (LN) metastasis. A total of 186 (63.9%) patients underwent surgery alone, 61 (21.0%) received CTx, whereas the remaining 44 (15.1%) patients received cXRT. At a median follow-up of 16.3 months, median and 5-year overall survival (OS) was 28.3 months and 33.0%, respectively. On multivariable analysis, factors associated with worse OS included AJCC T3/T4 (hazard ratio [HR] 2.97), LN metastasis (HR 1.75) and lymphovascular invasion (HR 1.98; all P<0.05). In contrast, receipt of CTx or cXRT was associated with improved long-term OS (CTx, HR 0.33; cXRT, HR 0.27; P<0.001) compared with surgery alone. Similar results were observed for disease-free survival (DFS)(CTx, HR 0.53; cXRT, HR 0.45; P<0.01). Of note, the OS benefit for CTx or cXRT was observed among patients with high risk features such as AJCC T3/T4 disease (HR 0.61; HR 0.31), LN-metastasis (HR 0.45; HR 0.46), and R1 disease (HR 0.33; HR 0.11) (all P<0.05). In contrast, the OS benefit of CTx and cXRT was not noted among patients with T1/T2 or N0 disease, or among those with an R0 margin (all P>0.05). Conclusions: Adjuvant CTx and cXRT were utilized in 36% of patients undergoing curative-intent resection for gallbladder cancer. After adjusted analysis, CTx and cXRT were independent factors associated with improved long-term outcomes, but the benefit was isolated to only patients with high-risk characteristics.