Abstract
Introduction-heterogeneity in clinical outcomes and survival was observed in patients with papillary thyroid cancer (PTC) and distant metastases. Here, we investigated the effect of distant metastases sites on survival in PTC patients. Methods-patients with a diagnosis of PTC and known metastases were identified using the Surveillance, Epidemiology, and End Results database (1975-2016). Univariate and multivariate Cox regression analyses were performed to analyze the effect of distant metastases sites on thyroid cancer-specific survival (TCSS) and overall survival (OS). Results-from 89,694 PTC patients, 1819 (2%) developed distant metastasis at the initial diagnosis, of whom 26.3% presented with the multiple-organ disease. The most common metastatic sites were lung (53.4%), followed by bone (28.1%), liver (8.3%), and brain (4.7%). In metastatic patients, thyroid cancer-specific death accounted for 73.2%. Kaplan-Meier curves showed decreased OS in patients with metastases to the brain (median OS = 5 months) and liver (median OS = 6 months) compared to lung (median OS = 10 months) and bone (median OS = 23 months). Moreover, multiple organ metastasis had a higher mortality rate (67.4%) compared to single organ metastasis (51.2%, p < 0.001). Using multivariate analysis, risk factors that significantly influence TCSS and OS were male gender (HR = 1.86, 95% CI = 1.17-2.94, p < 0.001, and HR = 1.90, 95% CI = 1.40-2.57, p = 0.009), higher tumor grade (HR = 7.31, 95% CI = 2.13-25.0, p < 0.001 and HR = 4.76, 95% CI = 3.93-5.76, p < 0.001), multiple organ involvement (HR = 6.52, 95% CI = 1.50-28.39, p = 0.026 and HR = 5.08, 95% CI = 1.21-21.30, p = 0.013), and brain metastasis (HR = 1.82, 95% CI = 1.15-2.89, p < 0.001 and HR = 4.21, 95% CI = 2.20-8.07, p = 0.010). Conclusion-the pattern of distant metastatic organ involvement was associated with variability in OS in PTC. Multi-organ metastasis and brain involvement are associated with lower survival rates in PTC. Knowledge of the patterns of distant metastasis is crucial to personalize the treatment and follow-up strategies.
Highlights
Thyroid cancers (TC) are the most common endocrine malignant tumors
A total of 212,651 thyroid cancer patients (1975–2016) from the SEER database were reviewed and only those with known metastasis were included in the analysis (n = 89,694 patients)
The median age of patients with metastasis at initial presentation was 65.38 ± 15.95 years compared to 50.25 ± 15.64 years in non-metastatic cohorts
Summary
Thyroid cancers (TC) are the most common endocrine malignant tumors. Their incidence is expected to be 44,280 in 2021, making them the 7th most common cancer in women in the U.S [1]. PTC arises from the follicular cells of the normal thyroid gland It is characterized by a papillary growth pattern of tumor cells with distinctive nuclear features as (1) overlapping and enlarged nuclei; (2) pale and optically clear; and (3) nuclear membrane irregularities [5]. DSV-PTCs represent 3% of all PTCs and include psammoma bodies and extensive calcification. These aggressive histological subtypes are associated with thyroid invasion, regional and distant metastasis. They present a significant reduction of patient overall survival, with a 5-year survival rate of 87.5% and 80.6% for DSV-PTC and TV-PTC, respectively [7,8,9]
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