[Carcinoid tumor and bone metastases: diagnosis by somatostatin receptor scintigraphy]

Knowns and unknowns of bone metastases in patients with neuroendocrine neoplasms: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to develop an evidence-based summary of current knowledge of bone metastases (BMs) in neuroendocrine neoplasms (NENs), inform diagnosis and treatment and standardise management between institutions.

METHODS

PubMed, Medline, EMBASE and meeting proceedings were searched for eligible studies reporting data on patients with BMs and NENs of any grade of differentiation and site; poorly-differentiated large/small cell lung cancer were excluded. Data were extracted and analysed using STATA v.12. Meta-analysis of proportions for calculation of estimated pooled prevalence of BM and calculation of weighted pooled frequency and weighted pooled mean for other variables of interest was performed .

RESULTS

A total of 149 studies met the eligibility criteria. Pooled prevalence of BMs was 18.4% (95% CI 15.4-21.5). BMs were mainly metachronous with initial diagnosis of NEN (61.2%) and predominantly osteoblastic; around 61% were multifocal, with a predisposition in axial skeleton. PET/CT seemed to provide (together with MRI) the highest sensitivity and specificity for BM detection. Almost half of patients (46.4%) reported BM-related symptoms: pain (66%) and skeletal-related events (SREs, fracture/spinal cord compression) (26.2%; weightedweighted mean time-to-SRE 9.9 months). Management of BMs was multimodal [bisphosphonates and bone-modifying agents (45.2%), external beam radiotherapy (34.9%), surgery (14.8%)] and supported by little evidence. Overall survival (OS) from the time of diagnosis of BMs was long [weighted mean 50.9 months (95% CI 40.0-61.9)]. Patients with BMs had shorter OS [48.8 months (95% CI 37.9-59.6)] compared to patients without BMs [87.4 months (95% CI 74.9-100.0); p = 0.001]. Poor performance status and BM-related symptoms were also associated with worse OS.

CONCLUSIONS

BMs in patients with NENs remain underdiagnosed and undertreated. Recommendations for management of BMs derived from current knowledge are provided. Prospective studies to inform management are required.

Primary neuroendocrine tumor of the sacrum: case report and review of the literature

Primary carcinoid tumor (well-differentiated neuroendocrine tumor) of the bone involving the sacrum is extremely rare. We report the case of a 72-year-old man who presented with a 20-year history of intermittent low back pain and was found to have an intraosseous sacral mass on imaging. A needle biopsy revealed that this lesion was a well-differentiated neuroendocrine tumor. Workup did not show any primary tumor or other metastatic disease. There was no associated tailgut cyst or sacrococcygeal teratoma. The lesion was treated with radiation therapy because a surgical approach was rejected. The patient is free of metastatic disease after 28 years evolution of the lesion, retrospectively seen to be present on a conventional radiography performed in 1980. A review of the literature revealed 20 case reports of neuroendocrine tumors arising from the presacral region (with or without associated tailgut cyst or sacrococcygeal teratoma) and sometimes extending to the sacrum. One additional case was located within the neural canal and involved the sacrum, the presacral region, and the rectal wall. Our case is the only tumor arising primarily from the sacrum. The long evolution of this lesion without any other location makes metastatic disease very improbable and this case appears to be a unique example of primary intraosseous sacral carcinoid tumor.