Survival and prognostic factors in well-differentiated pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (P-NETs) account for 2-3% of all pancreatic neoplasms. The aim of our study was to investigate survival and prognostic factors in patients with P-NETs.

We retrospectively reviewed the medical records of 114 patients diagnosed with well-differentiated P-NETs from 1982 through 2010. We studied demographical, clinical, radiological, and histopathological characteristics.

Median age at diagnosis was 57 years (range 32-83); 53% were men and 78% had nonfunctional tumors. The most common presenting symptoms were abdominal pain (41%), weight loss (36%), and diarrhea (25%); 19% of the tumors were incidental findings. Median duration of symptoms before diagnosis was 4 months, 3 months for nonfunctional, and 12 months for functional tumors (p < 0.001). At diagnosis, 32.5% patients had local, 22.8% had regional, and 44.7% had distant disease. Men had more often distant disease at diagnosis (p = 0.02). Median survival was 6.6 years (95% confidence interval [CI]: 4.0-9.2). Overall 5-year survival was 53.9% (95% CI: 43.4-63.3). For those with local disease and those with distant disease at diagnosis, the 5-year survivals were 70.2% (95% CI: 49.9-83.6) and 33.0% (95% CI: 19.7-46.7), respectively. Surgery with curative intent was performed on 46 patients. Newly detected liver metastases were diagnosed up to 10 years after surgery in this group. In patients with metastases, palliative surgery (debulking) did not have a significant effect on survival compared to those who had no surgery.

Distant metastases, Ki-67 > 2%, nonfunctional tumors, elevated level of chromogranin A, and palliative treatment were associated with poor survival.