Surveillance and comparison of surgical prognosis for asymptomatic and symptomatic non-functioning pancreatic neuroendocrine tumors.

Background: The treatment of non-functioning pancreatic neuroendocrine tumors (NF-PNETs) still remains controversial. It is uncertain whether asymptomatic patients have better prognosis than symptomatic patients and whether surgery is necessary for asymptomatic patients.

Methods: Patients with NF-PNETs who were managed surgically or by surveillance between June 2007 and December 2013 were retrospectively studied. The choice of surgery or surveillance was based entirely on the patient's desire. Survival prognosis was compared between asymptomatic and symptomatic patients, and evaluated among patients who were under surveillance.

Results: Of the 53 patients with NF-PNETs, 48 (90%) were treated surgically. 25 patients (47%) were symptomatic patients, 23 (43%) asymptomatic, and five (10%) detected by surveillance. Among the latter group, one patient suffered from tumor progression and four had stable disease. When compared with symptomatic NF-PNETs, asymptomatic NF-PNETs showed lower pathology grades (P = 0.006), better 3-year cumulative progression-free survival and overall survival after surgical treatment. Parenchyma-preserving resection was associated with a higher risk of pancreatic fistula (71 vs. 17%, P = 0.007). A positive lymph node status (P = 0.003) and perineural or vascular invasion (P = 0.01) were significant predictors of tumor recurrence or metastasis. Patients with grade G3 disease (P = 0.005) or a tumor size >4 cm (P = 0.019) had poor prognosis.

Conclusions: Compared with symptomatic NF-PNETs, asymptomatic NF-PNETs had a lower degree of malignancy and better prognosis. Surveillance for small asymptomatic NF-PNETs needs to be further studied.