Chemotherapy is associated with improved survival in a national cohort of stage IV pancreatic adenosquamous carcinoma

BACKGROUND: Pancreatic adenosquamous carcinoma (PASC) is a rare cancer that often presents with advanced disease and carries a grim prognosis. PASC is defined by the presence of at least 30% malignant squamous cells in the presence of malignant ductal adenocarcinoma. The utility of chemotherapy in the setting of metastatic disease is unknown. METHODS: In this cross-sectional analysis, patients with stage IV PASC diagnosed between 2006 and 2016 were abstracted from the National Cancer Data Base. Patients were then categorized according to whether they received chemotherapy. Multivariable logistic regression analysis was done to determine the odds of receiving palliative chemotherapy. Overall survival analysis was performed using Kaplan-Meier analysis. A Cox proportional hazard multivariable model was generated to account for potential confounders. RESULTS: There were 698 patients with metastatic PASC available for analysis, including 400 patients (57.3%) who received chemotherapy and 298 patients (42.3%) who did not receive chemotherapy. Median overall survival was significantly longer for patients who received chemotherapy (5.2 vs. 1.5 months, P<0.001; HR 0.328, 95% CI: 0.272–0.397). Compared to patients who did not receive chemotherapy, patients who received chemotherapy were younger (mean 62.6 vs. 70.1 years old; P<0.001) and more likely to have no comorbidities (72.0% vs. 58.7%; P<0.001). In multivariate analysis, chemotherapy was the only factor independently associated with improved survival. CONCLUSIONS: This is the largest study on PASC conducted to date and the first to evaluate whether chemotherapy is associated with improved survival for patients with metastatic disease. We found that palliative chemotherapy was associated with significant prolongation of life. However, overall prognosis remained dismal despite chemotherapy and novel treatment approaches are needed to improve long-term survival.