Endocrine Abstracts

Background: Current ENET guidelines inform our management of GCCs but we still have poor understanding of how these tumours behave in clinical practice.

Methods: We retrospectively analysed patients diagnosed with GCCs and entered prospectively into our tertiary referring centre’s NET database between 1990 and 2016.

Results: 41 patients (F:M ratio of 1.28:1) presented with GCC at a median age of 61 (range 27–79) years. Average tumour size 10.5 (range 0.5–50) mm. The most reliable IHC markers for GCC diagnosis CgA, SYP, and CD56, combined with CEA and cytokeratins (MNF-116 or CK20). The appendiceal tip was the most common site, accounting for 44% of aNETs. Appendicectomy was the most common diagnostic index operation in 78% of cases, followed by colectomy in 17%. 24 patients had completion surgery, comprising right hemicolectomy +/– bilateral oophorectomy, at a median of 3.0 (range 1.3–13.3) months after index resection. Histology from completion surgery showed residual disease in 8 patients comprising lymph nodes alone (n=2) or residual tumour alone (n=6). Univariate logistic regression did not identify any factors that significantly predicted likelihood of residual disease. Residual disease did not affect relapse (P=0.224) or death (P=0.511). Relapse occurred in 9 patients at a median of 57.0 (range 4.6–114.9) months. Univariate logistic regression did not identify any significant predictors of disease relapse. All patients with relapse died with the exception of one patient treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) who still remains alive. There were 10 deaths in our series, of which 9 were GCC-related. The 5-year and 10-year overall survival of GCC patients were 88% and 63%; both significantly affected by TNM stage (P<0.001) but not resection margin status (P≥0.242). The 5-year and 10-year progression free survival of NET patients were 73% and 50%; both significantly affected by TNM stage (P<0.001) but not by resection margin status (P≥0.092). Neither disease relapse nor death were significantly attenuated by completion surgery (P=0.482 for both).

Conclusion: GCC prognosis is poor and worsens with advancing TNM stage. Completion surgery is not effective and more radical treatments may need to be considered.