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Importance: Unlike for prostate cancer, active surveillance for thyroid cancer has not achieved wide adoption. The parameters by which this approach is feasible are also not well defined, nor is the effect of patient anxiety. Objective: To determine if expanded size/growth parameters for patients with low-risk thyroid cancer are viable, as well as to assess for cohort differences in anxiety. Design, Setting, and Participants: This prospective nonrandomized controlled trial was conducted at a US academic medical center from 2014 to 2021, with mean [SD] 37.1 [23.3]-month follow-up. Of 257 patients with 20-mm or smaller Bethesda 5 to 6 thyroid nodules, 222 (86.3%) enrolled and selected treatment with either active surveillance or immediate surgery. Delayed surgery was recommended for size growth larger than 5 mm or more than 100% volume growth. Patients completed the 18-item Thyroid Cancer Modified Anxiety Scale over time. Interventions: Active surveillance. Main Outcomes and Measures: Cumulative incidence and rate of size/volume growth. Results: Of the 222 patients enrolled, the median (IQR) age for the study population was 46.8 (36.6-58) years, and 76.1% were female. Overall, 112 patients (50.5%) underwent treatment with active surveillance. Median tumor size was 11.0 mm (IQR, 9-15), and larger tumors (10.1-20.0 mm) comprised 67 cases (59.8%). One hundred one (90.1%) continued to receive treatment with active surveillance, 46 (41.0%) had their tumors shrink, and 0 developed regional/distant metastases. Size growth of more than 5 mm was observed in 3.6% of cases, with cumulative incidence of 1.2% at 2 years and 10.8% at 5 years. Volumetric growth of more than 100% was observed in 7.1% of cases, with cumulative incidence of 2.2% at 2 years and 13.7% at 5 years. Of 110 patients who elected to undergo immediate surgery, 21 (19.1%) had equivocal-risk features discovered on final pathology. Disease severity for all such patients remained classified as stage I. Disease-specific and overall survival rates in both cohorts were 100%. On multivariable analysis, immediate surgery patients exhibited significantly higher baseline anxiety levels compared with active surveillance patients (estimated difference in anxiety scores between groups at baseline, 0.39; 95% CI, 0.22-0.55; P < .001). This difference endured over time, even after intervention (estimated difference at 4-year follow-up, 0.50; 95% CI, 0.21-0.79; P = .001). Conclusions and Relevance: The results of this nonrandomized controlled trial suggest that a more permissive active surveillance strategy encompassing most diagnosed thyroid cancers appears viable. Equivocal-risk pathologic features exist in a subset of cases that can be safely treated, but suggest the need for more granular risk stratification. Surgery and surveillance cohorts possess oppositional levels of worry, elevating the importance of shared decision-making when patients face treatment equivalence. Trial Registration: ClinicalTrials.gov Identifier: NCT02609685.
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Background: Active surveillance is established as an alternative to surgery for papillary thyroid microcarcinomas, but inclusion criteria and mortality risk for pursuing a nonsurgical approach have not been clearly defined. To gauge the feasibility of expanding active surveillance thresholds, we investigated the effects of increasing size and age on disease-specific survival (DSS) in a large nonoperative thyroid cancer cohort, compared against a matched group of surgical patients. Methods: Papillary thyroid carcinoma patients staged T1-4N0M0 were identified in the Surveillance, Epidemiology, and End Results (SEER) database between 1975 and 2015, stratified by nonsurgical and surgical management. Propensity score matching was performed to adjust for imbalances in covariates. Multivariable models were constructed using restricted cubic splines to model nonlinear relationships of age and tumor size with DSS. Results: Overall, 1453 nonoperative patients and 54,718 surgical patients met the inclusion criteria. Collectively, increasing age and size after certain thresholds independently led to greater differences in DSS between nonsurgical and surgical patients. For younger ages (14-55 years), surgical approach compared with nonsurgical approach was not associated with any difference in the 10-year DSS among 0-4 cm cancers (99.8% vs. 100%, p = 0.470), 4.1-6 cm cancers (98.8% vs. 100%, p = 0.599), or >6 cm cancers (97.3% vs. 100%, p = 0.718). Older patients with larger tumors (>75 years, >6 cm) demonstrated the greatest difference in DSS (48.1% vs. 91.3%, p < 0.001). Similar results were found when applying propensity score matching. For age, restricted cubic spline plots showed minimal relative survival hazard in nonoperative cases beginning after age 60 years, with a change point illustrating acceleration in relative hazard beyond age 72 years. For size, relative survival hazard was observed after 2.0 cm and increased slowly with nodule growth up to an inflection point of 4.5 cm. Beyond this, mortality risk escalated with each additional year without plateau. Conclusions: Increasing age and size lead to progressively greater mortality risk without surgery, but only beyond certain thresholds. We define escalating gradients at which a nonsurgical approach may be deemed appropriate, and beyond which survival benefits from surgery become apparent. Such findings reconcile controversial observations regarding age and size in active surveillance and further reshape evolving treatment paradigms in thyroid cancer.
