Head and body/tail pancreatic neuroendocrine tumors have different biological characteristics and clinical outcomes

Abstract

Purpose: The incidence of pancreatic neuroendocrine tumors (pNETs) has continued to increase, but for pNETs, there is still no distinction between treatments based on anatomical location. We aim to determine whether NETs located at the head and body/tail of the pancreas are different.

Patients and methods: Within the Surveillance, Epidemiology, and End Results database (2004-2016), we focused on pNETs patients with comprehensive information. The patients were divided into two groups based on tumors' location. We compared the characteristics of the two groups and assessed the risk factors for lymphatic metastasis. Survival analysis was performed based on the biological characteristics of the tumor.

Results: In all 3011 patients, pNETs were more common in the body/tail (62.94%) than in the head (37.06%) of the pancreas. The risk factors for lymph node metastasis in the two groups were different. Nonmetastatic, low-grade pancreatic body/tail NETs had the best prognosis (p < 0.001). For low-grade tumors (G1-G2), lymphatic metastasis did not significantly affect the prognosis of patients with pancreatic head NETs (p = 0.098) but affected the overall survival of patients with pancreatic body/tail NETs (p < 0.001). The tumors at the pancreatic head were larger (p = 0.001), more likely to have positive lymph nodes (p < 0.001) and more prone to locally advanced and distant invasion (p < 0.001). The prognosis of pancreatic head NETs 21-40 mm was worse than that of body/tail pNETs (p < 0.001). For non-functional NETs, the overall survival of pancreatic body/tail tumors was better (p < 0.001).

Conclusion: The pancreatic head and pancreatic body/tail NETs have different biological characteristics and clinical outcomes and they should be treated differently.

Keywords: Clinical outcomes; Pancreatic neuroendocrine tumors; Prognosis; Tumor biological characteristics.

Fig. 1

Survival analysis based on surgery. a Patients with a pancreatic head tumor. b Patients with a pancreatic body/tail tumor. c Patients with a pancreatic head and body/tail tumor without surgical treatment. d Patients with a pancreatic head and body/tail tumor with surgical treatment. PHG pancreatic head group, PBTG pancreatic body/tail group; these abbreviations are used throughout the paper. p < 0.05 was considered a significant difference

Fig. 2

Survival analysis based on lymph node metastasis and lymphadenectomy. a Patients with lymphadenectomy grouped by anatomical position. b Patients with lymphadenectomy grouped by lymph node metastasis and anatomical position. PHG-LNMG patients in the pancreatic head group without lymph node metastasis, PHG-LMG patients in the pancreatic head group with lymph node metastasis, PBTG-LNMG patients in the pancreatic body/tail group without lymph node metastasis, PBTG-LNMG patients in the pancreatic body/tail group with lymph node metastasis. These abbreviations are used throughout the whole paper. p < 0.05 was considered a significant difference

Fig. 3

Survival analysis based on lymph node metastasis and tumor grade. a Patients with a lower-grade (G1–G2) pancreatic head tumor with or without lymph node metastasis. b Patients with a higher-grade (G3–G4) pancreatic head tumor with or without lymph node metastasis. c Patients who had a lower-grade (G1–G2) pancreatic body/tail tumor with or without lymph node metastasis. d Patients who had a higher-grade (G3–G4) pancreatic body/tail tumor with or without lymph node metastasis. e Patients who had a pancreatic head and body/tail tumor (G1–G4) without lymph node metastasis. f Patients who had a pancreatic head and body/tail tumor (G1–G4) with lymph node metastasis. p < 0.05 was considered a significant difference

Fig. 4

Survival analysis based on tumor size. a Patients with 0–20 mm tumors. b Patients with 21–40 mm tumors. c Patients with tumors larger than 40 mm. p < 0.05 was considered a significant difference

Fig. 5

Survival analysis based on tumor size and lymph node metastasis. a Patients with a 0–20 mm tumor with or without lymph node metastasis. b Patients with a 21–40 mm tumor with or without lymph node metastasis. c Patients with a tumor larger than 40 mm with or without lymph node metastasis. p < 0.05 was considered a significant difference

Fig. 6

Survival analysis based on whether the tumor is functional. a Patients who have a functional pNET. b Patients who have a non-functional tumor