Endocrine Abstracts

Background: Neuroendocrine tumours (NETs) are often associated with SPMs. This study aimed to identify SPMs in patients with non-pulmonary wdNETs.

Methods: Patients seen at The Christie with non-pulmonary wdNETs from 2003–2017 were included. After exclusion of patients with hereditary predispositions, notes were retrospectively reviewed for location, functionality, treatment and temporal relation to diagnosis.

Results: Of 854 patients, 100 (11.7%) had a SPM. Median age at diagnosis of NET: 67 years (range 19–86); 51 females, 66%: grade (G)1, 22%: G2, 12% unknown. Sites of NET in order of prevalence: small bowel [SB](55%), pancreas (22%), unknown (13%), appendix (3%), stomach (3%) and other (4%). Median survival of patients with NET diagnosis was 48.5 months. Regarding first SPM diagnosed, 56 were diagnosed prior, 27 synchronous and 17 metachronous to NET; 85, 13 and 2 patients had one, two and three SPMs, respectively. Breast was the most common site of SPM (n=20, 80% curative), followed by colon (n=18, 100% curative), skin (n=13, 100% curative) and prostate (n=12, 100% curative); 15 other sites of SPM recorded. Colorectal and breast cancer were the most common SPM for patients with a SB-NET and pancreatic NET (pNET) diagnosis, respectively. Forty-four NETs were diagnosed incidentally. Of 21 patients with a SPM post-NET diagnosis, 12 had non-functional NETs, 3 functional, 6 unknown.

Conclusion: Non-pulmonary wdNETs are associated with high rates of SPMs. Most SPMs are diagnosed pre-NET, potentially indicating treatment-induced selection of neuroendocrine differentiation clones. A high proportion of NETs are diagnosed incidentally. The association between colorectal cancer and SB-NETs supports previous propositions of colonoscopy use in the work up to NET diagnosis, and association of breast cancer and pNET diagnosis may suggest a possible common pathway alteration in phosphoinositide-3-kinase (PI3K)/protein kinase-B (AkT)/mTOR pathway. Tumourigenic peptides secreted by functional NETs do not appear to have an impact on SPM development within the cohort of patients that develop SPM post-NET.