Large database utilization in health outcomes research in pancreatic cancer: an update

We sought to review published aggregate dataset studies on pancreatic cancer in the national and international settings, discuss the advantages and disadvantages these datasets possess, and possible future directions. A combination of Google Scholar, PubMed, and MEDLINE were used with search terms "pancreatic cancer" + "resectable" + "national cancer database", "pancreatic cancer" + "unresectable" + "national cancer database" and more broadly "borderline resectable pancreatic cancer", "locally advanced pancreatic cancer", "unresectable pancreatic cancer", and "resectable pancreatic cancer". Original articles and abstracts from this search were included, including data from the Surveillance, Epidemiology, and End Results (SEER) database, National Cancer Database (NCDB), and SEER-Medicare within the United States (US), as well as international database studies. Multiple database studies have been published regarding the role for radiotherapy in resected pancreatic cancer (n=6), the timing of additional therapy in resectable pancreatic cancer (n=4), and the role for radiotherapy and resection in locally advanced pancreatic cancer (LAPC) (n=4). Studies from both SEER and NCDB found a survival benefit to post-operative radiotherapy. In resectable pancreatic cancer, neoadjuvant treatment was found to be superior to adjuvant (NCDB). Chemoradiotherapy was found to be more beneficial than chemotherapy alone in LAPC, and patients who received highly-conformal or stereotactic body radiotherapy (SBRT) had improved survival compared to either conformal radiotherapy or chemotherapy alone. These studies also found that up to 10% of patients underwent resection, with a 90% margin-negative rate, and either one-half to one-third the risk of death of non-surgical patients. Criticism of large datasets includes lack of granularity of performance status, diagnosis, treatment, and outcomes-related data compared to properly administered prospective trials, as well as cross-over between treatment arms that cannot be accounted for, and concerns over quality of data represented. The US has witnessed a growing number of comparative effectiveness studies in pancreatic cancer. When taken together, certain themes emerge that are consistent with both single-institution data and clinical trials. These studies have also provided insight into questions not readily answerable by clinical trials. However, they require caution in interpretation.