Absence of Symptoms Does Not Indicate Benign Behavior in Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (pNETs) are less aggressive than the more common pancreatic ductal adenocarcinoma, and they tend to have better outcomes.

In recent years, many non-functioning pNETS (NF-pNETs) have been diagnosed incidentally during high-resolution imaging for another indication. When discovered early, NF-pNETs tend to be smaller than symptomatic pNETs, and unsurprisingly, curative resection and improved survival have been reported to be more likely.

A new study published in the January 2014 issue of Surgery compared a cohort of 124 patients with incidental NF-pNETs to 231 patients with symptomatic NF-pNETs in order to differentiate clinical and pathologic characteristics and survival rates. Over the study’s 18-year duration, the incidence of incidental tumors increased from 9% to 40%.

According to the researchers, the tumors that were symptomatic at diagnosis tended to be larger in size and more invasive to the microvasculature and neural areas compared to incidental tumors. Although most of the incidental NF-pNETs were at stages I or II, 30% of the tumors presented at stages III or IV.

The authors confirmed that patients with incidental tumors had better outcomes, and they reported 5-year progression-free survival rates of 32% and 83% in patients with and without symptoms, respectively. However, the researchers expected better survival rates in patients with incidental tumors, so they were surprised when the rates were not higher.

The authors concluded that an absence of symptoms does not indicate benign behavior in pNETs, as nearly one-third of patients with incidental tumors present with advanced disease.