Briggler, Andrew M.

420 Background: Advanced biliary cancers respond poorly to chemotherapy and have a dismal survival. Currently gemcitabine-cisplatin (GC) is the standard of care for patients with advanced disease. The efficacy of second line treatment options is not well-defined. We retrospectively evaluated outcomes of patients undergoing second line treatment for advanced biliary cancers at Mayo Clinic. Methods: After obtaining approval from the institutional board review (IRB), we identified 42 patients with advanced and metastatic biliary cancers that progressed after first line (GC) and received second line treatment from 2007-2014. All patients had adequate follow up data. JMP software was used for statistical analysis. Kaplan-Meier method and log-rank tests were used for survival analysis, and multivariate cox proportional hazards model was used to evaluate the prognostic effect of pertinent clinical variables. All tests were two sided and a P value of < 0.05 was considered significant. Results: The median age at diagnosis was 61.5 (range 26-87). The most common regimens used for second line settings were 5-FU-based (69%) followed by gemcitabine-based regimens (19%). The overall response rate (ORR) was 9.1%, while the disease control rate (DCR; stable disease and partial response) was 33%. The median overall survival (mOS) for the entire cohort from first line was 16.8 months (95% CI 12.7-21.7) and the progression-free survival (PFS) was 9.16 months (95% CI 7.3-14.7). From second line start the mOS was 10.4 months (95%; CI 7.3-23.7), and PFS was 2.8 months (95% CI 2.3-4.0). 73% of patients who received second line therapy were alive at 6 months and 50% at 12 months. 25 patients received third line treatment after progression. An univariate and multivariate analysis were performed including age, sex, stage at diagnosis, regimen used, CA19-9 and total body weight loss > 5%, but no significant prognostic factors were identified. Conclusions: Patients with biliary cancers who progress after first line treatment have poor prognosis, but may benefit from second line regimens. 5-FU based regimens were the most commonly used in the second line setting, and 73% of patients who received second line therapy were alive at 6 months.

179 Background: GISTs arise from interstitial cells of Cajal anywhere within the gastrointestinal tract, but those of the esophagus and GEJ are exceedingly rare ( < 1% of cases). Our aim was to characterize clinicopathological features and outcomes of esophageal and GEJ GISTs and compare survival with a population-based registry (SEER). Methods: 28 cases were identified using the Mayo Clinic Cancer Registry from 1997 to 2016, and 378 cases from the SEER 18 registry from 2000 to 2013. Mayo cases were re-reviewed by Mayo pathologists. We analyzed patient characteristics, tumor location, TNM staging, mitotic index, molecular diagnostics, IHC staining, and histomorphology. JMP software was used to calculate time to recurrence (TTR) and overall survival (OS) utilizing Kaplan-Meier and log-rank. Results: At Mayo, 60% of tumors arose in the distal esophagus. Mean tumor size was 5.73 cm. 42% of cases were low grade. None had nodal involvement. Five cases were metastatic at diagnosis, all to the liver. 86.7% had spindle cell morphology. IHC staining was positive for KIT in 92%, followed by CD34 (52%), DOG-1 (24%), and actin (16%). Mutational analysis was done on 10 cases and KIT mutation was found in 8 cases; 2 were wild-type. Two-thirds of patients underwent surgery, mostly esophagectomy. 14 patients received adjuvant imatinib. Median time to diagnosis from symptom onset was 2 months; median time to surgery from diagnosis was 1 month. Of 10 patients with complete follow-up, 2 had recurrences: 1at the anastomotic site and 1 in the liver. Median TTR from surgery was 36.5 months. Median follow-up time was 31.5 months. Median OS from diagnosis for the Mayo cohort was 129.5 months (95% CI 55.7-x). SEER cohort median OS was 81 months (95% CI 63-101), and females had superior OS compared to males (HR 0.67; 95% CI 0.48-0.93, p = 0.016). Conclusions: Patients undergoing surgical resection for esophageal and GEJ GISTs had a favorable prognosis, but recurrences occurred. The superior OS seen in the Mayo cohort suggests early resection and adjuvant imatinib may improve outcomes.