Mixed Adeno-Neuroendocrine Carcinoma (MANEC) of the Gastrointestinal (GI) Tract: Experience of a European Neuroendocrine Tumour Society (ENETS) Centre of Excellence

Introduction: Knowledge of MANECs is limited Aim(s): Outcomes of patients (pts) with GI MANEC were evaluated Materials and methods: Demographic/clinicopathological/survival data of consecutive pts with MANEC (2010 WHO criteria) were reviewed retrospectively Results: Twenty-five pts were identified (01/06-10/16); median (med) age: 71yrs (range 36-89), 56% male, ECOG PS 0-1: 48%. Primary tumour location; lower GI: 18(72%), upper: 7(28%). The neuroendocrine (NE) component (predominant histology in 44%) was poorly-differentiated (PD) in 24(96%) [Ki-67≥55%: 60%]. Most frequently expressed IHC markers were synaptophysin (100%), CDX2 (76%), CGA (64%). Of 13(52%) pts with localised disease (LA), 12(92%) had curative surgery (2 had neoadjuvant chemoradiotherapy (CR), 1 adjuvant chemotherapy (CT), 1 peri-operative CT) and 1(8%) had definitive CR; 6(46%) recurred. Sixteen pts (64%) were treated for advanced (adv) disease; 7(44%) platinum-based CT, 1(6%) gemcitabine, 8(50%) best supportive care (BSC). Med follow-up was 8.2mo (95%CI 4.5-16.8). Med OS for entire cohort was 14.6mo (95%CI 8.4–not reached [NR]). Med RFS and OS in pts with LA was 15.7mo (95%CI 5.8–NR) and 33.1mo (95%CI 8.4–NR) respectively. Med PFS in pts with adv disease was 3.5mo (95%CI 2–9.1). On univariable analysis, age<70 and adult comorbidity evaluation index (0 vs ≥1) was prognostic for better OS (both p<0.05) Conclusion: The NE component in MANECs was predominantly PD and CT and BSC were offered to pts with adv disease in equal proportion.