Hemicolectomy or appendectomy for appendiceal neuroendocrine tumours sized 1-2 cm? a retrospective population-based study of 1,581 patients

Tan Ker Shiong; Aya Abdelhameed; Mohamed Mortagy; White Benjamin E; John Ramage

doi:10.1530/endoabs.114.P5

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Endocrine Abstracts (2025) 114 P5 | DOI: 10.1530/endoabs.114.P5

UKINETS2025 23rd National Conference of the UK and Ireland Neuroendocrine Tumour Society 2025 Poster Presentations (33 abstracts)

Hemicolectomy or appendectomy for appendiceal neuroendocrine tumours sized 1-2 cm? a retrospective population-based study of 1,581 patients

Ker Shiong Tan ¹ , Aya Abdelhameed ² , Mohamed Mortagy ^3,4 , Benjamin E White ¹ & John Ramage ^1,5

Author affiliations

¹Gastroenterology Department, Hampshire Hospital NHS Foundation Trust, Basingstoke, United Kingdom; ²Alexandria University Faculty of Medicine, Alexandria, Egypt; ³Hampshire Hospital NHS Foundation Trust, Basingstoke, United Kingdom; ⁴St Georges University School of Medicine, Grenada, Grenada; ⁵University of Winchester, Winchester, United Kingdom

Background: Appendiceal neuroendocrine tumours (aNET) have a good prognosis and are commonly found at appendicectomy. aNET > 2 cm has high recurrence rates, and thus, right hemicolectomy (RHC) is advised. However, aNET < 1 cm generally does not recur. Management of aNET 1-2 cm is subject to debate. Nesti et al , 2023 suggested that RHC is not needed for tumours 1-2 cm in size, but long-term follow-up was needed.

Methods: This is a retrospective population-based study. A total of 1,304 adult patients with aNET 1-2 cm (diagnosed 2012-2022) who had appendectomy or RHC were extracted from the SEER database. Similarly, a total of 277 patients (diagnosed 2012-2021) were extracted from NCRAS database. Kaplan Meier (KM) plots for Overall survival (OS) and log-rank test (LR) were generated. Univariable and multivariable Cox regression for overall mortality were performed.

Results: In the SEER cohort, 997 and 307 patients underwent appendectomy and RHC, respectively. Median age, along with interquartile range (IQR), was 42.3 years (30.0-50.0) for appendectomy and 46.9 years (30.0-60.0) for RHC, respectively. Most patients were females (65.3%) and white patients (67.7%). Most patients had grade 1 (85.5%) aNET. Patients who underwent RHC had a higher proportion of N1 stage (18.9% vs. 2.9%) and M1 stage (2.6% vs 0.4%). The KM plot and LR test for OS showed no statistical difference between appendectomy and RHC (P = 0.22). A Fine-Gray competing risks model and KM plot with LR after propensity score matching showed the same result. In the NCRAS cohort, 162 and 115 patients underwent appendectomy and RHC, respectively. The median age, along with the IQR, was 39.5 years (25.2-57.0) for appendectomy and 51.0 years (36.0-70.0) for RHC, respectively. Patients who underwent RHC had a higher proportion of N1 stage (14.8%) and M1 stage (4.35%). The KM plot for OS showed no statistical difference between appendectomy and RHC (P = 0.07). Sex and race distribution were statistically not different between the two groups in NCRAS and SEER.

Conclusion: This study corroborates the findings of other recent smaller studies indicating that RHC may not be needed in aNET of 1-2 cm even with positive lymph nodes.