Incidental diagnosis as prognostic factor in different tumor stages of nonfunctioning pancreatic endocrine tumors

Incidentally discovered nonfunctioning pancreatic endocrine tumors (NF-pNETs) increasingly are being detected, and their management is debated. Moreover, the prognostic importance of incidental diagnosis for locally advanced or metastatic NF-pNETs is unknown. The aim of this study is to analyze the outcomes of incidentally discovered/symptomatic NF-pNETs stratified by tumor stage. A preliminary experience with nonoperative treatment of incidental NF-pNETs is reported.

Consecutive patients with symptomatic/incidental NF-PETs observed between 1990 and 2009 were analyzed, with different tumor stages considered. Nonoperative management of incidental NF-pNETs was evaluated.

Among 355 patients with NF-pNETs, the diagnosis was incidental in 124 (35%). Incidental NF-pNETs were associated more commonly with lower tumor stages compared with symptomatic tumors (P < .0001), but 30% of incidental NF-pNETs were stage III-IV. Incidental NF-pNETs had greater rates of radical resections and of R0 margins (P < .0001). Five-year progression-free survival (PFS) was 83% and 32% for incidental and symptomatic NF-pNETs, respectively (P < .0001). Five-year PFS was better for incidental NF-pNETs compared with symptomatic tumors for each tumor stage, including stage III (69% vs 27%, P < .0001) and stage IV (60% vs 17%, P = .112). After a median follow-up of 36 months, there was no tumor progression in 12 patients who underwent nonoperative management of incidental NF-pNETs.

A total of 30% of incidental NF-pNETs present with stage III-IV disease. PFS is much greater for incidental NF-pNETs compared with symptomatic patients, and this difference is evident also for stage III-IV tumors, suggesting that absence of symptoms may indicate a less-aggressive disease. Nonoperative management can be an alternative to surgery in selected incidental NF-pNETs.