Long-term follow-up of asymptomatic pancreatic neuroendocrine tumors in multiple endocrine neoplasia type I syndrome.

BACKGROUND AND AIMS

Pancreatic neuroendocrine tumors (PNETs) in asymptomatic patients may contribute to mortality. Endoscopic ultrasound (EUS) is the most accurate test to identify and monitor tumor size. The aim of this study was to examine the rate of growth and development of new tumors in multiple endocrine neoplasia type I (MEN 1).

MATERIALS AND METHODS

A retrospective cohort study in a tertiary academic center. Patients identified in endoscopic databases were included if they had 2 or more EUS examinations with untreated asymptomatic tumors identified. The growth rate and incidence of new lesions was analyzed.

RESULTS

A total of 11 patients were studied (7 female, 4 male). Initially, 18 lesions with an average size of 10.3 mm (range, 5 to 24 mm) were found. Mean surveillance was 79 months (range, 18 to 134 mo). The growth rate of index lesions was 1.32 mm/y; 11 lesions exhibited stability or a decrease in size. Twelve new lesions were identified in 7 patients during the surveillance period with an average growth rate of 3.0 mm/y. The earliest new lesion was identified at 12 months and the latest at 70 months after index EUS. New lesions had a faster growth rate than those seen on initial EUS (P=0.01).

CONCLUSIONS

Multiple endocrine neoplasia type I patients exhibit an overall low rate of growth of pancreatic neuroendocrine tumors. Growth rate of newly diagnosed lesions was significantly faster, suggesting a variation in phenotypic expression of the disease. Therapy should be individualized based upon the tumor size and location, symptoms, overall clinical status, and operative risk.