Endocrine Abstracts

Introduction

Insulinomas are the most common functional neuroendocrine tumours of the pancreas. Because previous data on the long-term prognosis of insulinoma patients are scarce, we wanted to study the morbidity and mortality in Finnish patients previously treated for an insulinoma.

Patients and methods

The Finnish insulinoma register consists of all adult patients diagnosed with an insulinoma in Finland during 1980–2010, including two patients with a MEN1 syndrome (n = 79). For each patient, 4 controls were chosen from the Finnish Population Register Centre, matched for age, gender and the place of residence, and alive at the diagnosis of the corresponding patient (n = 316). Morbidity due to endocrine, cardiovascular, gastrointestinal and mental disorders, and cancers was compared between the patients and controls by analysing the incidence rate ratios (RR) with the 95% Confidence Intervals (95% CI) using the Mantel–Haenszel method. Kaplan–Meier and Cox regression analyses were used to compare the overall survival (OS) of the patients and controls.

Results

Seventy (89%) of the insulinomas were non-metastatic and 9 (11%) were metastatic. The median length of follow-up after the insulinoma diagnosis was 11 (0.2–33) years for the patients and 12 (1.2–35) years for the controls. Morbidity due to thyroid disorders [RR 2.76 (95% CI 1.00–7.60], parathyroid disorders (RR not applicable), atrial fibrillation [RR 2.02 (95% CI 1.00–4.09)], intestinal obstruction [RR 18.65 (95% CI 2.09–166.86)], non-insulinoma pancreatic diseases [RR 13.04 (95% CI 2.12–20.36)], abdominal hernias [in patients with a non-metastatic insulinoma, RR 2.33 (95% CI 1.00–5.43)], breast cancer [RR 4.46 (95% CI 1.29–15.39] and kidney cancer (RR not applicable) was increased among insulinoma patients compared to controls, P <0.05 for all comparisons. Postoperative disease progression or recurrence occurred in 6 (8%) of the 71 patients who underwent curative-intent surgery, the 5- and 10-year disease-free survival being 96% and 94%. The OS of patients with a non-metastatic insulinoma did not significantly differ from that of controls, but for patients with a metastatic insulinoma, the OS was significantly impaired, with a median survival of 3.4 years. In multivariate analyses, older age and distant metastases were associated with a decreased OS.

Conclusions

The long-term prognosis of patients with non-metastatic insulinomas is similar to the general population, except for an increased incidence of thyroid and parathyroid disorders, atrial fibrillation, intestinal obstruction, non-insulinoma pancreatic diseases, abdominal hernias, and breast and kidney cancers. Metastatic insulinomas are rare, but entail a markedly decreased survival.