The real-world selection of first-line systemic therapy regimen for metastatic gastroenteropancreatic neuroendocrine neoplasm in Japan

In November 2013, the first edition of evidence-based guidelines for treatment of gastroenteropancreatic neuroendocrine neoplasm (GEP-NEN) was published in Japan. However, whether medical practitioners have adopted the first-line regimens recommended for metastatic GEP-NEN in clinical practice is not yet known. The purpose of this study was to identify which first-line systemic therapy regimens have been selected and the proportion of cases that are adherent to the guidelines (i.e., number of patients receiving recommended therapy/total number of patients). We combined hospital-based cancer registry data and insurance claims-equivalent data for patients with GEP-NEN treated between January 2013 and December 2014 and extracted those with metastatic GEP-NEN who received systemic therapy. The proportions that were adherent with the guideline were calculated according to tumor classification (neuroendocrine tumor [NET] or neuroendocrine carcinoma [NEC]), primary site (gastrointestinal or pancreatic), and hospital volume (high, medium, or low). The study included 109 patients with GEP-NET and 424 with GEP-NEC. Overall, guideline-adherent treatment was provided in only 54.8% of cases (58.1% for gastrointestinal NET, 63.6% for pancreatic NET, 56.6% for gastrointestinal NEC, and 44.9% for pancreatic NEC). The recommended therapy for GEP-NET was used in 16.5% of patients with GEP-NEC, and 21.5% received fluoropyrimidine-containing chemotherapy. This report is the first to describe real-world selection of first-line regimens for metastatic GEP-NEN. About half of all these patients received systemic therapy that was not recommended in the guidelines.