Objectives: The aim of this study is to identify the prognostic factors predicting remission and subsequent disease relapse in patients with differentiated thyroid cancer (DTC) greater than 60years of age.
Materials and methods: The institute thyroid cancer database had 4370 patients with DTC, of which 447 (10%) were aged>60. However, 9 patients were excluded due to follow-up less than 1year. The prognostic factors in the remaining 438 patients were studied.
Results: Among the 438 patients, 311 (71%) had only loco-regional disease (M0) and 127 (29%) had distant metastases (M1) at the time of initial presentation. The host factors predictive of distant metastases at presentation were female gender, primary tumor size (>4cm), follicular histology, and extra-thyroidal extension. Among Mo patients, 195 (63%) achieved complete remission while only 12 (9%) M1 patients did so. Average number of radioactive iodine ((131)I) doses administered to achieve complete remission was 2.3 (range, 1-6) and the mean cumulative dose was 3404MBq (range, 925-46,250MBq). In multivariate logistic regression among M0 patients, follicular histology, nodal metastases, and surgical treatment lesser than total/near-total thyroidectomy and among M1 patients, site of distant metastases (skeletal and multiple sites) were independent factors predicting non-remission. Among the patients (both M0 and M1) who achieved remission, factors associated with disease recurrence were primary tumor size (>4cm), nodal metastases, pulmonary metastases, and non-remission after first dose of radioactive iodine and were associated with greater chances of disease relapse.
Conclusion: This study highlights that DTC in older patients behaves more aggressively than in adults age<60years, and identifies several prognostic factors for remission and subsequent relapse.
Keywords: Differentiated thyroid cancer; Elderly; Prognostic factors; Recurrence; Remission.
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