Comparison of prognosis between observation and surgical resection groups with small sporadic non-functional pancreatic neuroendocrine neoplasms without distant metastasis.

Background: The treatment of small (≤ 2 cm), sporadic localized non-functional pancreatic neuroendocrine neoplasms (PNENs) is often controversial. This study aimed to investigate the clinical outcomes with observation and surgical resection in small PNENs.

Methods: Seventy-five patients with small localized sporadic non-functional PNENs ≤ 2 cm, who underwent observation or surgical resection, were retrospectively reviewed. Changes in tumor size during follow-up in the observation group were also investigated.

Results: The median age of the cohort was 61 (range 35-81) years. The tumor grades were G1, G2, and unknown, in 61 (81.3%), 8 (10.7%), and 6 (8.0%) patients, respectively. The mean follow-up periods in the observation (n = 23) and surgical resection groups (n = 52) were 52.3 (range 6.8-133.3) months and 73.0 (range 9.1-179.9) months, respectively. The median overall survival was not reached. During follow-up, no patient died of PNENs, two died of other diseases, three had lymph node metastases, and one experienced recurrence after surgical resection. There was no significant difference in overall survival between the observation and surgical resection groups (hazard ratio: 0.031, P = 0.417). The mean change in tumor size in the observation group was + 0.30 mm (range - 1.6 to + 3.0 mm). No deaths, tumor progression, lymph node metastases, distant metastases, or recurrence were noted in patients with PNENs ≤ 1 cm (n = 36).

Conclusions: The prognosis of small localized PNENs is good. Observation may be an alternative to surgery in high-risk patients and those with small G1 tumors, particularly those measuring ≤ 1 cm.