title: Features Associated With Metastases Among Well-Differentiated Neuroendocrine (Carcinoid) Tumors of the Appendix: The Significance of Small Vessel Invasion in Addition to Size.
abstract: BACKGROUND
  The risk of metastatic disease among carcinoid tumors of the appendix increases with tumor size. However, it is unclear if any features other than size are also associated with an increased risk of metastatic disease.
  
  
  OBJECTIVE
  The aim of this study was to review the characteristics of appendiceal carcinoid tumors and determine if other histologic features besides size should guide surgical decision making.
  
  
  METHODS
  This study involved a retrospective case series.
  
  
  METHODS
  This study was conducted at a single tertiary acute care hospital.
  
  
  METHODS
  Patients diagnosed with an appendiceal carcinoid tumor between 2000 and 2014 were identified. Goblet cell carcinoids, adenocarcinomas with neuroendocrine features, and tumors from other primary locations were excluded.
  
  
  METHODS
  Simple appendectomy or segmental/total colectomy with lymphadenectomy was performed.
  
  
  METHODS
  The primary outcomes measured were metastases, recurrence, and overall survival.
  
  
  RESULTS
  Seventy-nine patients were included. The overall incidence of metastatic disease was 10%. Patients with metastatic disease were more likely to be male (75% vs 28%, p = 0.008), have small-vessel invasion (43% vs 5%, p = 0.001), and have larger tumors (median 2.0 cm vs 0.5 cm, p < 0.001). Among tumors <2 cm, the incidence of metastases among tumors with small-vessel invasion was 60% compared with 0% among those without small-vessel invasion (p < 0.001). Among tumors ≥2 cm, the incidence of metastases was 50% irrespective of small-vessel invasion. If small-vessel invasion was used as a second indication for performing a right hemicolectomy along with size ≥2 cm, both the sensitivity and negative predictive value would have been 100% compared with 63% and 96% if size was used alone. Patients with metastatic disease had a higher incidence of recurrence (13% vs 0%, p = 0.003), but overall survival was 100% in both groups.
  
  
  CONCLUSIONS
  Small sample size, retrospective design, and limited long-term follow-up were the limitations of this study.
  
  
  CONCLUSIONS
  Carcinoid tumors of the appendix <2 cm with small-vessel invasion have similar metastatic potential as tumors ≥2 cm. Therefore, a recommendation for a right hemicolectomy should be considered for tumors <2 cm with small-vessel invasion. Additional prospective multicenter studies are warranted.
authors.affiliation: Department of Surgery, New York Presbyterian Hospital - Weill Cornell Medical College, New York, New York.
authors.forename: David A
authors.initials: DA
authors.lastname: Kleiman
authors.forename: Brendan
authors.initials: B
authors.lastname: Finnerty
authors.forename: Toni
authors.initials: T
authors.lastname: Beninato
authors.forename: Rasa
authors.initials: R
authors.lastname: Zarnegar
authors.forename: Govind
authors.initials: G
authors.lastname: Nandakumar
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Fahey
authors.forename: Sang W
authors.initials: SW
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D001062:Appendectomy; D001063:Appendiceal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D002276:Carcinoid Tumor / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D003082:Colectomy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D047368:Tumor Burden