Thyroid cancer has progressively increased by 4.5 percent every year during the previous decade. Thyroid cancer is expected to overtake colorectal cancer to become the third most frequent disease in women by 2019. In the United States, 95% of thyroid cancer patients were identified with localised or regional illness, whereas 5% presented with distant disease. Despite the favourable prognosis of patients with localized/regional illness (99 percent 5-year survival rate), survival declined dramatically when distant metastases were present. Thyroid cancer metastases are most commonly seen in the bones. Bone is a favourable habitat for tumour cell development, and it typically indicates a poor prognosis. Because of the incidence of skeletal-related events, bone metastases produce a significant level of morbidity (SREs). Pathologic fractures, spinal cord compression, the requirement for bone irradiation, or the necessity for bone surgery are all SREs. Although much research has been done on bone metastases and SREs in other malignancies, little is known about bone metastases and SREs in thyroid cancer. Because complete data on the prevalence and consequences of bone metastases and SREs is insufficient, we used the Surveillance Epidemiology and End Results (SEER)-Medicare database to conduct a large population-based analysis of all patients with thyroid cancer diagnosed between 1991 and 2011. We looked at the influence of variables that increase the risk of bone events on overall and diseasespecific mortality in addition to identifying factors that increase the risk of bone events. The existence of bone events, we expected, would be an independent predictor of poor outcome. Patients were divided into three groups based on their SEER stage at the time of diagnosis: localised illness limited to the original site, regional disease with dissemination to regional lymph nodes, and distant disease with signs of metastasis. The analyses were omitted because to missing data on race (n=218, 0.7 percent), household income (n=2721, 9.1 percent), high school diploma (n=2721, 9.1 percent), tumour size (n=3517, 11.7 percent), and unknown/other stage (n=770, 2.5 percent). After missing data was removed, the total number of patients was 26,350. The occurrence of bone metastases or SREs was characterised as a bone event. We identified patients with bone metastases and SREs using ICD9 and CPT-4 codes. Pathologic fractures, spinal cord compression, the requirement for bone radiation, and bone surgery were all considered SREs. These two sets of codes can be used to identify claims involving SREs. Refer to the Supplementary Data for more information on the ICD-9 and CPT-4 codes used.
