The impact of minimal extrathyroidal extension in the recurrence of papillary thyroid cancer patients

ABSTRACT Objective We aimed to evaluate the impact of minimal extrathyroidal extension (mETE) alone on the risk of recurrence of papillary thyroid carcinoma (PTC). The impact of other factors, including multifocality, age, tumor size, and stimulated thyroglobulin (sTg) values was also assessed. Subjects and methods We retrospectively analyzed 1,108 PTC patients from a medical institution, who presented tumors ≤ 4 cm without any adverse characteristics other than mETE. Patients were classified according to their response to initial treatment 12 to 24 months after surgery as proposed by the 2015 American Thyroid Association (ATA) guideline. Statistical analysis was performed using multivariate logistic regression and receiver operating characteristic (ROC) curve. Results In the multivariate logistic regression analysis, mETE did not have an impact on the response to initial treatment (p = 0.44), similar to multifocality, age, and tumor size. Initial Tg value was the only variable associated with a poor response (p < 0.01, odds ratio = 1.303, 95% confidence interval 1.25-1.36). The ROC analysis revealed that Tg was significant (area under curve = 0.8750); the cutoff value of sTg as a predictor of poor response was 10 ng/mL (sensitivity = 72.2%, specificity = 98.5%). Conclusion For low-risk PTC presenting mETE as the only aggressive feature, the initial sTg value is essential to identify patients who may have a poor response after initial treatment and benefit from further treatment. Arch Endocrinol Metab. 2020;64(3):251-6

Prognostic Significance of Minimal Extrathyroidal Extension of Papillary Thyroid Carcinomas / 대한내분비외과학회지

PURPOSE: Extrathyroidal extension (ETE) is a risk factor for the recurrence of a papillary thyroid carcinoma (PTC). In the TNM 6(th) classification system, an extrathyroidal invasion of a differentiated thyroid carcinoma has been classified as T3 (minimal invasion), T4a (extended invasion), and T4b (more extensive unresectable invasion) according to tumor invasion. We investigated the clinicopathologic characteristics, recurrence, and disease-free survival (DFS) of minimal ETE (mETE). METHODS: We retrospectively evaluated 332 patients who underwent a thyroidectomy for PTC from January 2005 to December 2006. RESULTS: Of the 332 patients, 103 (31.0%) were found to have a PTC with mETE and 229 (69.0%) patients had a PTC without mETE. In PTC, mETE was related to gender, tumor size, multifocality, Lymph node (LN) metastasis, underlying Hashimoto's thyroiditis, and surgery. But there is no significant difference in age, recurrence, and LN metastasis between the mETE and No mETE groups. Multivariate analysis demonstrated that LN metastasis (odds ratio=2.273; 95% confidence interval 1.280~4.037) was recognized as an independent factor for mETE (P=0.005). Disease-free survival was not significantly different between patients with and without mETE (P=0.153). We analyzed the effect of LN metastasis in groups with and without mETE. Based on the presence or absence of LN metastasis, disease-free survival (DFS) rates between each group showed no significant differences. CONCLUSION: Minimal ETE had no impact on DFS in patients with PTC. Therefore, an appropriate surgical approach and postoperative follow-up are required for tumors with mETE.

The Definition of Minimal Extrathyroid Extension in Thyroid Pathology by Analyzing Sizable Intra- and Extrathyroid Blood Vessels

BACKGROUND: To define the exact boundary of the intrathyroid and extrathyroid aspects of a gland when determining the extent of cancer invasion, we plan to clarify the definition of sizable vascular structures, which is one of the helpful histologic clues in determining a minimal extrathyroid extension. We hypothesized that arterial wall thicknesses in extrathyroid soft tissue would be significantly different from the arteries in the thyroid parenchyma. METHODS: Twenty cases of papillary carcinoma were selected. The numbers and wall thicknesses of the arteries and arterioles in intrathyroid and extrathyroid tissue were evaluated. The absence of nerve tissue in the thyroid gland was confirmed using the S-100 protein immunohistochemical stain. RESULTS: The comparison of the mean thicknesses of the total arteries between the extrathyroid and intrathyroid tissues in the retrospective study (26.88 micrometer vs. 15.07 micrometer, respectively) and the prospective study (35.24 micrometer vs. 16.52 micrometer, respectively) revealed significant differences (p=0.000). The greatest thickness of the intrathyroid arteries was 67.93 micrometer. CONCLUSIONS: According to our results, the study showed that the extrathyroidal arteries were significantly thicker than the intrathyroidal arteries. We suggest that the sizable blood vessels of extrathyroidal arteries should be greater than 67.93 micrometer in thickness.