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

The aim of this study has been to retrospectively assess the usefulness of 111In-DTPAOC scintigraphy in the detection of bone metastases (BM) in patients diagnosed of carcinoid tumour (CaT).

Between June 1995 and April 2003 78 111In-DTPAOC studies were consecutively performed in 58 patients, 31 females and 27 males, 28 to 73 years old, with a histological diagnosis of CaT. Moreover, whole body bone scans (BS) using 99mTc-MDP were performed in 13 of these patients. The patients were classified into three groups: Group A: Initial CaT staging (n = 23); Group B: CaT staging after surgery (n = 14); and Group C: Post-treatment CaT re-staging (n = 29). In this last group, 6 patients of group A and 2 patients of group B were included. In only 2 patients the diagnoses of bone metastases were established before the 111In-DTPAOC scan.

Twenty six (44.8 %9 of the 58 patients with CaT had metastatic disease: 15 patients with hepatic metastases, associated with BM in 4 of them, 10 patients with hepatic and extra-hepatic metastases, abdominal and/or thoracic, associated with BM in 4 and in one patient, the BMs were the only metastases detected. The global incidence of BM in patients diagnosed with CaT was 15.5 % (9/58), whereas the incidence of BM in patients with metastasic disease was 34.6 % (9/26). Significant differences (p = 0.0035) were found on the incidence of BM in patients with or without hepatic metastases. In 4 patients, BMs were detected during the initial staging (group A), whereas in 5 patients, BMs were detected during the post-treatment re-staging (group C). During diagnosis, 4 of the 9 patients with BM had bone pain. BM were multiples in 8 patients, affecting axial skeleton in 4 and axial and appendicular skeleton in 4. One patient had a diffuse infiltration of bone marrow. BS was positive in 8 of the 9 patients with BM. In these 8 patients with abnormal BS, 111In-DTPAOC scintigraphy provides similar information to the BS in one patient, shows a greater number of bone lesions in 3, whereas BS was superior in 5 patients. Four of the patients with BM died between 6 and 47 months after diagnosis (mean: 29.7 months).

BMs are preferably located on axial skeleton, can be asymptomatic and are associated with hepatic metastases. Although the 111In-DTPAOC scintigraphy is able to detect some BM earlier than BS, the information provided by both studies is complementary. In patients with CaT, any invasive therapy on the hepatic metastases make it necessary to exclude extrahepatic metastases, including bone ones, and the somatostatin receptor scintigraphy is the diagnostic method of choice.