Long-term Prognosis for Non-functional Neuroendocrine Tumors of the Pancreatic Body and Tail ≤ 3cm

Long-term Prognosis Comparison Between Parenchyma-sparing and Oncologic Resections for Non-functional Neuroendocrine Tumors of the Pancreatic Body and Tail ≤ 3cm: a Real-world Data Study

This study aims to quantify the malignant potential of non-functional neuroendocrine tumors of the pancreatic body and tail ≤ 3 cm by collecting real-world data from large pancreatic centers across the country, and to evaluate the appropriateness of parenchyma-sparing resection and oncologic resection.

According to epidemiological investigations, the incidence of neuroendocrine tumors has increased 6.4-fold (6.98 per 100,000) . There is controversy in the latest guidelines regarding the management of sporadic non-functional pancreatic neuroendocrine tumors (pNETs) ≤ 2 cm, including follow-up and the choice between parenchyma-sparing resection (PSR) and oncologic resection (OR) . Although pNETs are generally considered indolent tumors, current experience suggests that 9.5%-12.3% of pNETs ≤ 2 cm may have lymph node metastasis, and nearly 20% of resected tumors exhibit one or more invasive features. Awareness of surgical treatment for these patients has been increasing gradually. However, there is no clear recommendation for the choice of surgical approach, and if OR is routinely performed, its prognostic value is unclear and there may be a risk of overtreatment.

The advantages of PSR include preservation of both endocrine and exocrine pancreatic function. However, the main oncological limitations of these techniques are inadequate surgical margin clearance and the risk of lack of lymph node dissection. A recent retrospective analysis of prospective databases from four large pancreatic surgery centers showed that for ≤ 3 cm non-functional pNETs, PSR or lymph node-preserving resection had less blood loss, shorter operation time, lower complications rate, and similar long-term oncological outcomes compared to OR. However, this study did not differentiate the tumor locations, as pNETs in the pancreatic head and body/tail have different lymphatic drainage patterns and surgical approaches. Furthermore, the study also showed significant differences in the proportion of PSR and the rate of positive lymph nodes between tumors located in the pancreatic head and those in the body/tail.

The ability of existing literature to provide reliable guidelines for pNETs is limited by the low incidence of the disease and short follow-up times. This study aims to quantify the malignant potential of pNETs of the pancreatic body and tail ≤ 3 cm by collecting real-world data from large pancreatic centers across the country, and to evaluate the appropriateness of PSR and OR.

Inclusion Criteria:

• Non-functional neuroendocrine tumors of the pancreatic body and tail ≤ 3 cm.

Exclusion Criteria:

• Presence of liver or distant metastasis.
• Presence of concomitant malignancy.
• Multifocal or recurrent disease.
• Presence of hereditary syndrome (MEN1, VHL, NF).
• Presence of symptoms (specific symptoms of clinical syndromes suspected to be related to excessive secretion of bioactive compounds).
• History of preoperative antitumor therapy.
• Loss to follow-up.