In a European retrospective cohort study reported in The Lancet Oncology, Nesti et al found evidence that right-sided hemicolectomy is not indicated in patients who had complete resection, via appendectomy, of appendiceal neuroendocrine tumors (NETs) measuring 1 to 2 cm.
As stated by the investigators: “Awareness of the potential global overtreatment of patients with appendiceal NETs of 1 to 2 cm in size by performing oncological resections is increasing, but the rarity of this tumor has impeded clear recommendations to date. We aimed to assess the malignant potential of appendiceal NETs of 1 to 2 cm in size in patients with or without right-sided hemicolectomy.”
The study involved pooled data from 40 hospitals in 15 European countries on patients of any age and Eastern Cooperative Oncology Group performance status with histopathologically confirmed appendiceal NETs of 1 to 2 cm who had complete resection of the primary tumor by appendectomy between January 2000 and December 2010. A total of 278 patients were identified, with 163 (59%) having appendectomy alone and 115 (41%) also having right-sided hemicolectomy.
Mean age at initial surgery was 36.0 years. Median follow-up was 13.0 years (interquartile range = 11.0–15.6 years).
A total of nine patients (3%) were found to have distant metastases, including four who underwent appendectomy alone and five who underwent right-sided hemicolectomy. On central histopathologic review, appendiceal NETs were classified as possibly (n = 1) or probably (n = 3) the origin of metastases in four patients, including two (1%) with distant peritoneal metastases and two with distant metastases in the liver. All four of these metastases were diagnosed synchronously with the appendiceal NET; none of the patients experienced tumor-related death during follow-up.
Regional lymph node metastases were found in 22 (20%) of 112 patients who underwent right-sided hemicolectomy with available data. No associations of these metastases with tumor location (P = .10), tumor grade (P = .17), lymphovascular invasion (P = .14), or mesoappendix infiltration (P = .36) were observed; resection margin was associated with presence of metastases (P = .023). On the basis of histopathologic risk factors, it was estimated that 12.8% of patients undergoing appendectomy alone probably had residual regional lymph node metastases.
At data cutoff, death had occurred in 20 (12%) of 163 patients who underwent appendectomy alone and in 13 (11%) of 115 patients who underwent right-sided hemicolectomy (adjusted hazard ratio = 0.88, 95% confidence interval [CI] = 0.36–2.17, P = .71). Estimated overall survival rates at 5, 10, 15, and 20 years were 96% (95% CI = 91%–98%) vs 94% (95% CI = 88%–97%), 92% (95% CI = 86%–95%) vs 91% (95% CI = 84%–95%), 87% (95% CI = 80%–92%) vs 87% (95% CI = 79%–93%), and 80% (95% CI = 70%–88%) vs 87% (95% CI = 79%–93%).
The investigators concluded: “This study provides evidence that right-sided hemicolectomy is not indicated after complete resection of an appendiceal NET of 1 to 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 histopathologic evaluation of risk factors is not supported by the presented results. These findings should inform consensus best practice guidelines for this patient cohort.”
Reto Martin Kaderli, MD, of the Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, Switzerland, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by the Swiss Cancer Research Foundation. For full disclosures of the study authors, visit thelancet.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.