Nodal metastases in small rectal neuroendocrine tumours

Aim Rectal neuroendocrine tumours (NETs) are the most common type of gastrointestinal NET. European Neuroendocrine Tumour Society guidelines suggest that rectal NETs measuring ≤10 mm are indolent with low risk of spread. In practice, many patients with lesions ≤1 cm do not undergo complete tumour staging. However, the size of the lesion may not be the only risk factor for nodal involvement/metastases. The aim of this study was to determine if MRI ± nuclear medicine imaging alters tumour stage in patients with rectal NETs ≤10 mm. Methods Patients referred to a tertiary NET centre between 2005 and 2020 who met the inclusion criteria of a rectal NET ≤10 mm, full cross‐sectional imaging, primarily an MRI scan and, if abnormal findings were identified, a subsequent 68Ga‐DOTATATE positron emission tomography scan were included. All patients were followed up at our institution. Results In all, 32 patients with rectal NETs 10 mm or less were included in the study: 16 women; median age 58 years (range 33–71); 47% (n = 15) were referred from bowel cancer screening procedures. The median size of the lesions was 5 mm (range 2–10 mm). 81% (n = 26) were World Health Organization Grade 1 tumours with Ki67