Long-term scintigraphic and clinical follow up in patients with differentiated thyroid cancer and iodine avid bone metastases

Abstract

Aim The aim of this study was to evaluate the long-term overall therapy outcomes and clinicopathological risk factors in patients with differentiated thyroid cancer (DTC) and iodine avid bone metastases. Methods Our study included 93 patients [female to male ratio (2:1)]. All patients were subjected to clinical examination, laboratory assessment, I-131 whole body scan, and neck ultrasound. Iodine avid metastases were treated with successive radioactive iodine-131 (RAI-131) doses. The overall response was defined as complete response (CR), incomplete response (IR) [partial response (PR) and stable disease (SD)], and progressive disease (PD). Results Fifty-four patients had follicular carcinoma and 39 with papillary type. Isolated bone metastases, bone and lung metastases, and multi-organ metastases were found in 45, 34, and 14 patients, respectively. The overall CR, PR, SD, and PD were found in 8.6%, 28%, 46.2%, and 17.2% patients, respectively. Adjunctive radiotherapy resulted in more CR, IR, and low PD rates compared to RAI-131 therapy (9.0%, 78.3%, 12.7% vs. 7.9%, 56.8%, and 23.7%, respectively) (P = 0.03). The overall survival rate was 88.2% and median follow-up period was 123 months. Female patients, papillary carcinoma, and single focal lesion had better overall response rate. Males, extrathyroidal extension, vascular invasion, and lymph nodes metastases had increased PD and decreased global response rates. Conclusion Despite of low CR rate (8.6%), most patients with DTC and iodine avid bone metastases had SD (46.2%) and long lived (88.2%). Adjunctive radiotherapy reduced PD and improved outcome. Males, extra thyroid extension and vascular invasion were bad prognostic factors.

Bone Metastases

“…Several single-photon oncologic tracers have the ability to detect and monitor therapy response in bone metastases and usually have the additional benefit of detecting soft tissue disease as well. These radiopharmaceuticals tend to be disease-specific, for example, [ 131 I]iodine in thyroid cancer or ( 111 In]octreotide and [ 99m Tc]EDDA-HYNIC-TOC in neuroendocrine tumors, 43,44 often acting as theranostic agents for planning and assessing response to radionuclide therapy with respective therapeutic radiopharmaceuticals, although equivalent diagnostic PET isotopes also exist, e.g., [124 I]iodine 45 and [ 68 Ga]DOTATATE 15 …”