Abstract

CALIFANO, I et al. Outcome of Bone Metastases in 47 Patients with Differentiated Thyroid Cancer. Rev. argent. endocrinol. metab. [online]. 2014, vol.51, n.2, pp.51-58. ISSN 1851-3034.

Distant metastasis is an infrequent event in patients with differentiated thyroid cancer (DTC) and it occurs approximately in 10 % of cases. Bone is the second metastatic site in patients with DTC. The aim of this multicenter retrospective study was to describe the diagnosis and treatment of bone metas­tases (BMs) in patients followed up in ten different hospitals from Argentina. Diagnosis of BMs was made when: a) BM was confirmed by biopsy, b) a structural bone lesion was found following 131I uptake associated with elevated levels of serum thyroglobulin (Tg) or c) a structural bone lesion was demonstrated by 18FDG uptake on PET/CT, also associated with high levels of serum Tg. Demographical, clinical, pathological and outcome data were obtained from hospital charts. We included 47 patients: 55 % were women, with a median age of 55 years old. Histology of DTC was as follows: 55 % had papillary thyroid cancer, 32 % had follicular thyroid cancer and 13 % had other variants. Diagnosis of BMs were synchronous in 47 % of patients (at the same time as DTC diagnosis) and metachro­nous in 53 %, occurring within a mean period of 72 months after initial diagnosis. In 64 % of patients, BMs were symptomatic: pain was referred in 70 % of these cases. In 68 % of cases, there were multiple sites of BMs, with the spine being the most frequent localization (36 %). In 68 % of patients, other distant metastases were observed, mainly in the lungs. Stimulated Tg levels were known in 38 patients at diagnosis: > 100 ng/ml in 87 % and <100ng/ml in 13 %. Serum calcium level was normal in all subjects in whom it was measured (n = 41). In 9 (29 %) of the 31 patients studied, serum bone turnover markers were elevated. At least one modality of treatment was prescribed in 96 % of patients with BMs. Radioiodine was indicated in 78 % of cases, bisphophonates were prescribed in 64 % of patients, while surgery was performed in 53 %. In 55 % of cases, external beam radiotherapy was also indicated and 23 % of individuals received other therapeutic approaches. Median follow-up was 24 months (range 1-228 months). The survival rate at the end of follow-up was 41 %. One patient (3 %) was considered to have no evidence of disease, 28 patients (59 %) died as a consequence of the DTC. The cause of death was known in 27 cases and it was related to BMs in only 8 patients (30 %). In conclusion, BMs were mainly observed in patients >45 years old, with similar gender distribution. BMs were multiple and had mainly an axial skeletal localization, causing high morbidity in most patients. Although bone turnover markers were elevated in one third of cases, no patient had hypercalcemia. Multiple modali­ties of treatment were used in the majority of cases, which indicates the importance of a multidisciplinary approach. Finally, although BMs were associated with incurable disease, mortality was mainly related to the spread of DTC to other sites, and not specifically to BM. Rev Argent Endocrinol Metab 51:51-58, 2014 No financial conflicts of interest exist.

Keywords : Bone metastases; Thyroid cancer.

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