P19: Pathological Features Associated With Lymph Node Disease in Patients with Appendiceal Neuroendocrine Tumors.

Friday, March 24, 2023

10:41 AM – 10:46 AM

Location: SSO HUB Pan-Tumor Zone: CRS, HPB, Pan-Tumor & Upper GI

Poster Presenter(s)

Salvador Rodriguez Franco, MD (he/him/his)

Senior Research Associate
Department of Surgery, University of Colorado Anschutz Medical Campus
Aurora, Colorado, United States

Disclosure information not submitted.

Author(s)

Madeline B. Thomas, MD (she/her/hers)

Resident
University of Colorado School of Medicine, Department of Surgery
Denver, Colorado, United States

Disclosure information not submitted.
AK

Andrii Khomiak, MD

Resident
University of Colorado School of Medicine, Department of Surgery, United States

Disclosure information not submitted.
LA

Lia R. Assumpção, MD, PhD

Assistant Professor of Surgery
Department of Surgery, Rio de Janeiro State University, Rio de Janeiro, Brazil, United States

Disclosure information not submitted.
Toshitaka Sugawara, MD, PhD

Visiting Researcher
University of Colorado School of Medicine
Denver, Colorado, United States

Disclosure information not submitted.
PC

Paul Choi, MD

Resident
University of Colorado School of Medicine, Department of Surgery, United States

Disclosure information not submitted.
Camille Stewart, MD

Assistant Professor of Surgery
University of Colorado Anschutz Medical Center

Disclosure information not submitted.
BM

Benedetto Mungo, MD

Assistant Professor of Surgery
University of Colorado Anschutz Medical Campus, United States

Disclosure information not submitted.
MD

Marco Del Chiaro, MD, PhD, FACS

Professor
University of Colorado School of Medicine, Department of Surgery, Division of Surgical Oncology, United States

Disclosure information not submitted.
RS

Richard Schulick, MD, MBA, FACS

Chair
University of Colorado School of Medicine, Department of Surgery, Division of Surgical Oncology, United States

Disclosure information not submitted.
Martin McCarter, MD

Professor of Surgery
University of Colorado School of Medicine

Disclosure information not submitted.
Steven Ahrendt, MD

Professor of Surgery
University of Colorado Anschutz Medical Campus
Aurora, Colorado, United States

Disclosure information not submitted.
AG

Ana Gleisner, MD, PhD

Associate Professor
Department of Surgery, University of Colorado Anschutz Medical Campus, United States

Disclosure information not submitted.

Introduction: Appendiceal neuroendocrine tumors (ANETs) are well known for their slow progression; nonetheless, the presence of lymph node metastasis has been described in up to 50% of all cases. Following an appendectomy, patients at high risk for nodal disease, based on the tumor size and location, are considered for a right hemicolectomy. However, presence of high-risk pathologic features, such as lymphovascular invasion (LVI), tumor extension beyond the submucosa (EBS), and nodal metastasis are controversial regarding need for further surgery.

Methods: We included patients ≥18yrs of age with ANETs from the National Cancer Database (NCDB) who underwent at least a partial colectomy between 2004 to 2017. Groups were defined based on lymph node status as N- (all examined nodes were negative) and N+ (≥ 1 examined nodes were positive). Patient demographics and oncological features were analyzed by multivariable analysis to identify factors independently associated with nodal disease. The predicted probability of N+ was estimated based on the presence of high-risk pathologic features.

Results: A total of 2,465 cases were included. Among these, 23% had lymph node metastases, including 33 of 979 patients with tumors < 1 cm (3.3%), and 145 of 696 patients with tumors ≥1 cm but ≤2 cm (20.8%). Age, tumor size, depth of tumor invasion, and presence of lymphovascular invasion (LVI) were significantly associated with N+ (p < 0.001). In patients with tumors < 1 cm, the predicted probability of N+ disease with invasion beyond the submucosa but no LVI was less than 3%. Risk increased to greater than 10% in the presence of both, invasion beyond submucosa and LVI (table 1). In the 703 (28.5%) patients who had less than 12 lymph nodes evaluated, the rate of N+ was lower compared to patients who had 12+ lymph nodes examined (12.1% vs. 26.1%, p< 0.001).

Conclusions: In ANETs, the presence of LVI and tumor invasion beyond the submucosa are associated with increased risk of nodal metastasis independent of the tumor size. Patients with < 12 lymph nodes evaluated after colectomy may not be appropriately staged. These factors should be taken into consideration when discussing the need for additional surgery in patients with appendiceal NET who underwent an appendectomy alone.

Learning Objectives:

Upon completion, the participant will be able to identify risk features for nodal disease in ANETs
Upon completion, the participant will be able to estimate the risk of nodal disease in small ANETs
Upon completion, the participant will be able to discuss the optimal surgical option in patients with high-risk features