Use of Adjuvant Radiation Therapy in the Management of Acinar Cell Carcinoma of the Pancreas: Results From the Survival, Epidemiology, and End Results Database

Abstract

Acinar cell carcinoma (ACC) is an extremely rare cancer of the pancreas, accounting for less than 1 % of non-endocrine pancreatic tumors. The role for adjuvant radiation therapy (RT) in the management of this disease is unknown. The Survival, Epidemiology, and End Results 18 database, November 2012 submission, was queried for ACC of the pancreas reported between the years of 1998 and 2010. Baseline characteristics were compared with the chi-squared test. Overall survival (OS) and cause-specific survival (CSS) were estimated using the Kaplan–Meier method. Cox proportional hazard modeling was performed for multivariate analysis of factors associated with OS and CSS. Analyses were performed using SPSS, version 20. Two hundred nineteen patients with acinar cell carcinoma were identified. Median follow-up was 11 months. Median patient age was 66 (range 4–92). One hundred fourteen patients (52.1 %) had locoregional disease, while 105 patients (47.9 %) had metastatic disease at diagnosis. Median OS for all patients was 14 months (95 % confidence interval (CI) 9.24–18.77 months), and median CSS was 17 months (95 % CI 10.37–23.63 months). For patients with non-metastatic disease, median OS was 38 months (95 % CI 28.43–47.57). Among patients with non-metastatic disease, the use of adjuvant radiation was associated with increased median OS (56 months [95 % CI 21.67–90.33]), compared to patients not treated with radiation (27 months [95 % CI 4.06–49.94]), p = 0.046. Use of adjuvant radiation was associated with increased cause-specific survival (66 vs. 40 months), but this was not statistically significant (p = 0.104). On multivariate analysis, use of surgery and adjuvant radiation were both associated with improved OS for patients with non-metastatic disease (hazard ratio (HR) 0.517, p = 0.034 and HR 0.423, p = 0.009, respectively). Both surgery and radiation were associated with non-statistically significant improvement in ACC cause-specific survival, HR = 0.606 (95 % CI = 0.314–1.170), p = 0.136 and HR = 0.501 (95 % CI = 0.249–1.009), p = 0.053, respectively. Surgical resection with curative intent followed by adjuvant RT is associated with excellent long-term overall survival in patients with non-metastatic local-regional acinar cell carcinoma of the pancreas.