Purpose The 2025 American Thyroid Association guideline supports consideration of lobectomy (LT) for low-risk 2–4 cm differentiated thyroid cancer (DTC), but evidence on cancer-specific death (CSD) in this “gray zone” is limited. We used a population-based cohort to evaluate associations of LT versus total thyroidectomy (TT) with CSD and to develop an exploratory CSD-prediction tool. Methods Using SEER 2000–2022 data, we included intrathyroidal 2–4 cm N0M0 DTC treated with LT or TT without radiotherapy or chemotherapy. After 1:1 propensity-score matching, overall and cancer-specific survival were analyzed. CSD and other-cause death (OCD) were evaluated using Fine–Gray competing-risk models, and independent predictors were incorporated into a nomogram. Results We identified 4,192 patients and matched 1,620 (810 LT; 810 TT). LT was not associated with higher overall or cancer-specific mortality. In multivariable Fine–Gray models, TT showed higher subdistribution hazard of CSD, although this association may reflect residual confounding. Subgroup analyses suggested that lower-risk scenarios—tumors 21–30 mm, unifocal disease, and no lymph-node evaluation—were associated with lower CSD with LT, whereas differences were attenuated for 31–40 mm tumors or multifocal disease. The nomogram demonstrated acceptable discrimination and calibration for exploratory CSD risk stratification. Conclusion In a strictly defined ATA-2025 low-risk 2–4 cm DTC cohort, LT was not associated with higher CSD compared with TT. The competing-risk nomogram may provide exploratory individualized risk stratification rather than direct guidance for surgical selection in this “gray-zone” population.
Wang et al. (Mon,) studied this question.
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