Purpose Primary ovarian neuroendocrine tumors (NETs) develop in pure form or in association with other tumors, mainly teratomas. The available data regarding this rare condition are limited. Much of the literature focuses on single case reports, previously dismissed as a totally benign disorder, and thus long-term considerations and evidence-based management guidelines are lacking. The objective of the current study was to describe the clinical and pathologic characteristics and the effect of various therapeutic modalities on patient morbidity and mortality from 2 major centers. A secondary objective was to highlight that carcinoid syndrome may be manifest in the absence of metastatic disease.

Methods The authors retrospectively studied a cohort of 34 consecutive patients with primary ovarian NETs who attended either the Oxford University Hospitals or Beatson Oncology Centre, Glasgow, between 1984 and 2014, and had their ovarian carcinoid data (eg, tumor growth, chemotherapy regimen) and mortality outcomes assessed.

Results All patients were women, with an average age of 53 years (range, 23–87 years) at diagnosis. Of the 34 patients, 8 patients (23.5%) presented with carcinoid symptoms. Carcinoid heart disease was evident in 2 of the 34 patients (6%). All patients had a primary ovarian carcinoid tumor on histopathology, and 2 patients had bilateral ovarian carcinoids. Teratoma associations could be assessed in 29 tumors, with 20 (69%) of 29 showing a pathological association. The mean tumor size was 48 mm (range, 4–120 mm; SD, 40 mm). The mean follow-up was 4.5 years, ranging up to 17 years. The disease has been quiescent with no evidence of relapse in 22 of 34 patients; in 12 of 34 patients, it was metastatic. There were 5 patients who received treatment with somatostatin analogs or chemotherapy, whereas 8 patients (23.5%) died of disease. Metastatic disease was found up to 11 years from initial diagnosis.

Conclusions Primary ovarian NET is rare and likely underrepresented in the literature. It can no longer be simply dismissed as a generally benign entity and may present with both the carcinoid syndrome and carcinoid heart disease. It requires careful evaluation and long-term review.