Endocrinol Metab.  2023 Feb;38(1):93-103. 10.3803/EnM.2023.1667.

Lower Thyroid Cancer Mortality in Patients Detected by Screening: A Meta-Analysis

• Moon S
• Song YS
• Jung KY
• Lee EK
• Park YJ

• KMID: 2539823
• DOI: http://doi.org/10.3803/EnM.2023.1667

Abstract

Background
Thyroid cancer screening has contributed to the skyrocketing prevalence of thyroid cancer. However, the true benefit of thyroid cancer screening is not fully understood. This study aimed to evaluate the impact of screening on the clinical outcomes of thyroid cancer by comparing incidental thyroid cancer (ITC) with non-incidental thyroid cancer (NITC) through a meta-analysis.
Methods
PubMed and Embase were searched from inception to September 2022. We estimated and compared the prevalence of high-risk features (aggressive histology of thyroid cancer, extrathyroidal extension, metastasis to regional lymph nodes or distant organs, and advanced tumor-node-metastasis [TNM] stage), thyroid cancer-specific death, and recurrence in the ITC and NITC groups. We also calculated pooled risks and 95% confidence intervals (CIs) of the outcomes derived from these two groups.
Results
From 1,078 studies screened, 14 were included. In comparison to NITC, the ITC group had a lower incidence of aggressive histology (odds ratio [OR], 0.46; 95% CI, 0.31 to 0.7), smaller tumors (mean difference, −7.9 mm; 95% CI, −10.2 to −5.6), lymph node metastasis (OR, 0.64; 95% CI, 0.48 to 0.86), and distant metastasis (OR, 0.42; 95% CI, 0.23 to 0.77). The risks of recurrence and thyroid cancer-specific mortality were also lower in the ITC group (OR, 0.42; 95% CI, 0.25 to 0.71 and OR, 0.46; 95% CI, 0.28 to 0.74) than in the NITC group.
Conclusion
Our findings provide important evidence of a survival benefit from the early detection of thyroid cancer compared to symptomatic thyroid cancer.

Keyword

Thyroid neoplasms; Mass screening; Ultrasonography

Figure

• 

  Figure 1. Flow diagram of study selection. aStudies that did not report the mortality/recurrence or pathologic characteristics of incidental thyroid cancer were excluded. Additionally, studies of patients with thyroid cancer risk factors, such as nuclear accidents and radiation exposure, were excluded.

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  Figure 2. Risk of bias assessment within studies using Risk of Bias Assessment of Non-randomized Studies (RoBANS).

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  Figure 3. Results of the meta-analysis for pathologic characteristics between the incidental thyroid cancer (ITC) and non-incidental thyroid cancer (NITC) groups. (A) Medullary thyroid cancer (MTC) or anaplastic thyroid cancer (ATC), (B) size, (C) extrathyroidal extension (ETE), (D) lymph node metastasis (LNM), (E) distant metastasis, and (F) advanced stage III to IV. OR, odds ratio; CI, confidence interval; SD, standard deviation; MD, mean difference.

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  Figure 4. Results of the meta-analysis for recurrence between the incidental thyroid cancer (ITC) and non-incidental thyroid cancer (NITC) groups. CI, confidence interval. aRecurrence and residual cancer.

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  Figure 5. Results of the meta-analysis for mortality between the incidental thyroid cancer (ITC) and non-incidental thyroid cancer (NITC) groups. CI, confidence interval. aThyroid cancer with distant metastasis.

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