Colon to Rectum

Lancet Oncol. 2023;24(2):187–94

Nesti C, Bräutigam K, Benavent M, Bernal L, Boharoon H, Botling J, Bouroumeau A, Brcic I, Brunner M, Cadiot G, Camara M, Christ E, Clerici T, Clift AK, Clouston H, Cobianchi L, Ćwikła JB, Daskalakis K, Frilling A, Garcia-Carbonero R, Grozinsky-Glasberg S, Hernando J, Hervieu V, Hofland J, Holmager P, Inzani F, Jann H, Jimenez-Fonseca P, Kaçmaz E, Kaemmerer D, Kaltsas G, Klimacek B, Knigge U, Kolasińska-Ćwikła A, Kolb W, Kos-Kudła B, Kunze CA, Landolfi S, La Rosa S, López López C, Lorenz K, Matter M, Mazal P, Mestre-Alagarda C, Morales del Burgo P, Nieveen van Dijkum EJM, Oleinikov K, Orci LA, Panzuto F, Pavel M, Perrier M, Reims HM, Rindi G, Rinke A, Rinzivillo M, Sagaert X, Satiroglu I, Selberherr A, Siebenhüner AR, Tesselaar MET, Thalhammer MJ, Thiis-Evensen E, Toumpanakis C, Vandamme T, van den Berg JG, Vanoli A, van Velthuysen MLF, Verslype C, Vorburger SA, Lugli A, Ramage J, Zwahlen M, Perren A, Kaderli RM

Hemicolectomy versus appendectomy for patients with appendiceal neuroendocrine tumors 1–2 cm in size: A retrospective, Europe-wide, pooled cohort study

Background: Awareness of the potential global overtreatment of patients with appendiceal neuroendocrine tumors (NETs) of 1–2 cm in size by performing oncological resections is increasing, but the rarity of this tumor has impeded clear recommendations to date. The authors aimed to assess the malignant potential of appendiceal NETs of 1–2 cm in size in patients with or without right-sided hemicolectomy.
Methods: In this retrospective cohort study, they pooled data from 40 hospitals in 15 European countries for patients of any age and Eastern Cooperative Oncology Group performance status with a histopathologically confirmed appendiceal NET of 1–2 cm in size who had a complete resection of the primary tumor between January 1, 2000, and December 31, 2010. Patients either had an appendectomy only or an appendectomy with oncological right-sided hemicolectomy or ileocecal resection. Predefined primary outcomes were the frequency of distant metastases and tumor-related mortality. Secondary outcomes included the frequency of regional lymph node metastases, the association between regional lymph node metastases and histopathological risk factors, and overall survival with or without right-sided hemicolectomy. Cox proportional hazards regression was used to estimate the relative all-cause mortality hazard associated with right-sided hemicolectomy compared with appendectomy alone.
Findings: 282 patients with suspected appendiceal tumors were identified, of whom 278 with an appendiceal NET of 1–2 cm in size were included. 163 (59%) had an appendectomy and 115 (41%) had a right-sided hemicolectomy, 110 (40%) were men, 168 (60%) were women, and mean age at initial surgery was 36.0 years (SD 18.2). Median follow-up was 13.0 years (interquartile range, 11.0–15.6). After centralized histopathological review, appendiceal NETs were classified as a possible or probable primary tumor in 2 (1%) of 278 patients with distant peritoneal metastases and in 2 (1%) of 278 patients with distant metastases in the liver. All metastases were diagnosed synchronously with no tumor-related deaths during follow-up. Regional lymph node metastases were found in 22 (20%) of 112 patients with right-sided hemicolectomy with available data. On the basis of histopathological risk factors, it was estimated that 12.8% (95% confidence interval [CI]: 6.5–21.1) of patients undergoing appendectomy probably had residual regional lymph node metastases. Overall survival was similar between patients with appendectomy and right-sided hemicolectomy (adjusted hazard ratio = 0.88 [95% CI: 0.36–2.17]; p = 0.71).

Interpretation: This study provides evidence that right-sided hemicolectomy is not indicated after complete resection of an appendiceal neuroendocrine tumor (NET) of 1–2 cm in size by appendectomy, that regional lymph node metastases of appendiceal NETs are clinically irrelevant, and that an additional postoperative exclusion of metastases and histopathological evaluation of risk factors is not supported by the presented results. These findings should inform consensus best practice guidelines for this patient cohort.

DOI: DOI: 10.1016/s1470-2045(22)00750-1