The Role of Surgery in Small Differentiated Thyroid Cancer

Abstract

<h3>Purpose/Objective(s)</h3> The incidence of small, differentiated thyroid cancer (DTC) cases has been increasing in the United States and the world. This increase is mainly due to incidental detection because of the wide use of diagnostic modalities. While the option of active surveillance instead of surgical resection is getting more popular, there is still an open discussion about the best approach in these cases. <h3>Materials/Methods</h3> The National Cancer Database was queried for patients diagnosed with non-metastatic small (T1/N0) DTC at age 18 or older between 2004 and 2016. After excluding patients with unknown surgery status, we evaluated the overall survival (OS) between patients who had surgical resection and patients who didn't have surgical resection. We studied the OS using Kaplan-Meier estimates and multivariate cox regression analyses to evaluate factors associated with OS. Additionally, propensity score matching (accounting for age, gender, race, Charlson-Deyo score, tumor size, and histology) was used for more robust results. <h3>Results</h3> A total of 98,501 patients with non-metastatic small DTC were included in the analysis, of which 96,612 (98.1%) had surgical resection, and 1,889 (1.9%) did not have surgical resection. We found that patients who had surgical resection had better OS compared to patients who did not have surgical resection (mean OS 171 months vs 134.1 months, P<0.001). Propensity score matching yielded 3778 patients for analysis of which 1889 (50%) patients had surgical resection and 1889 (50%) patients did not have surgical resection. We found patients who had surgical resection had statistically significant better OS compared to patients who did not have surgical resection (mean OS was 165.8 months vs 134.1 months, P < 0.001). Same trend was found in subgroup analysis when we split the cohort according to tumor size, histology type and Charlson-Deyo score; <1cm (mean OS was 169.3 months vs 138.3 months, P < 0.001), ≥1cm (mean OS was 171.6 months vs 131 months, P < 0.001), follicular (mean OS was 166.7 months vs 106.8 months, P < 0.001), papillary (mean OS was 170.8 months vs 136.3 months, P < 0.001), Hurthle cell carcinoma (mean OS was 166.5 months vs 72.5 months, P < 0.001), Charlson-Deyo score of 0-1 (mean OS was 171.6 months vs 135.5 months, P = 0.001) and Charlson-Deyo score of 2 (mean OS was 141 months vs 63.5 months, P < 0.001). On multivariate analysis, surgery was associated with better OS (HR 0.218; 95% CI: 0.196 - 0.244; P<0.001). <h3>Conclusion</h3> Patients with non-metastatic small DTC who were treated with surgical resection had statistically significant improvement in OS compared to patients who did not have surgical resection. Acknowledging the limitations of this retrospective analysis, these results urge for caution before rushing into recommending an active surveillance strategy for all patients with small, well-differentiated DTC.