[Treatment strategy for low-risk papillary thyroid carcinoma with diameter smaller than 1 cm: immediate surgery vs active surveillance]

The incidence of differentiated thyroid cancer is increasing rapidly worldwide, with subcentimeter papillary thyroid carcinoma (SPTC) with a diameter of less than 1 cm accounting for more than 50%. Active surveillance (AS) as an alternative to immediate surgery for low-risk SPTC was launched in Japan in the 1990s and has been implemented in several countries, including Japan and the United States. However, the indications and safety of performing AS for low-risk SPTC remain controversial. In this article, the author summarizes the existing literature and explores its limitations of AS implementation, the effectiveness of surgical treatment, and the different attitudes of countries on AS, aiming to provide some references for the treatment options of low-risk SPTC.

Dynamic estimates of survival in oncocytic cell carcinoma of the thyroid

BACKGROUND

Little is known about death hazard and conditional survival of oncocytic cell carcinoma of the thyroid (OCC).

METHODS

Patients diagnosed with OCC between 2004 to 2019 were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. The Kaplan-Meier method was used to estimate the actuarial disease-specific survival (DSS). The annual hazard rate of death was depicted employing the hazard function. Based on the life-table method, the conditional DSS was calculated.

RESULTS

In terms of DSS rates, there were statistically significant differences among the different stages (P < 0.01). Annual hazard curves for mortality from OCC in the entire study participants demonstrated an overall decreasing tendency with two peaks at 3 and 10 years. In patients with distant disease, the death risk curve was the steepest and decreased quickly and evidently. Conditional DSS tended to increase over time in the entire study population. Patients with distant disease showed more significant alterations than those patients with local or regional disease.

CONCLUSIONS

Prognosis improved over time in patients with OCC. The largest increase in conditional DSS was observed in patients with distant disease. Conditional survival may provide more relevant prognostic information than conventional survival estimates and allow personalized follow-up and counseling.

[Status in clinical and molecular characteristics of differentiated thyroid carcinoma in children and adolescents]

The epidemiological, clinical, and molecular characteristics of differentiated thyroid carcinoma (DTC) in children and adolescents are different from those in adults. The incidence of DTC in children and adolescents is very low, with high rates of lymph node metastasis, extra-thyroidal extension and recurrence, but mortality is lower than that in adults. Younger children with DTC tend to show a higher rate of recurrence, more lymph node metastases, and more extra-thyroidal extension. Furthermore, studies on molecular characteristics suggest that the diversity of gene mutations causes the clinical manifestations of DTC in children and adolescents that are different from those in adults. The incidence of gene fusion is significantly higher than in adults, while the incidence of point mutations is lower than in adults, which may be closely related to clinicopathological characteristics such as high tumor aggressiveness and poor prognosis.

[Analysis of clinicopathological characteristics and prognosis of papillary thyroid carcinoma in children and adolescents at different ages]

Objectives: To examine the age cut-off point for poor clinicopathological characteristics and prognosis of differentiated thyroid carcinoma (DTC) in children and adolescents. Methods: The clinicopathological features of 74 patients with DTC aged 18 years and younger who underwent surgery in the Department of Thyroid Surgery, the First Hospital of China Medical University from January 2011 to December 2020 were retrospectively analyzed. There were 20 males and 54 females, aged (M(IQR)) 16 (4) years (range: 8 to 18 years). Firstly, the cut-off point of age affecting prognosis was determined according to the receiver operator characteristic curve, the patients included in the study were grouped according to the age cut-off, and then the univariate and multivariate analysis for prognostic factors were performed using the Cox risk proportional regression model. The Kaplan-Meier survival curve was used to verify the factors affecting the prognosis and analyzed the possible mechanisms by bioinformatics. Results: The cut-off value of age was 15 years. Age ≤15 years was the only prognostic factor for recurrence (HR=4.427, 95%CI: 1.236 to 15.859, P=0.022). The number of metastatic cervical lymph nodes was higher in patients aged ≤15 years, and the 10-year recurrence-free survival rate was much lower than in patients aged >15 years (50.4% vs. 84.1%, P=0.018). Gene enrichment analysis and differential gene identification showed that differential genes between ≤15 years old group and>15 years old group were closely related to the transforming growth factor-β signaling pathway and some metabolism-related signaling pathways. Conclusions: Age ≤15 years is the only prognostic factor for the prognosis of DTC in children and adolescents. Age ≤15 years had more cervical lymph node metastases and a worse prognosis. For younger DTC patients, more active treatment and a stricter postoperative management strategy should be adopted.

LncRNA GAS8-AS1 inhibits cell proliferation through ATG5-mediated autophagy in papillary thyroid cancer

PURPOSE

The long non-coding RNA GAS8 antisense RNA 1 (lncRNA GAS8-AS1) is a tumor suppressor in papillary thyroid cancer (PTC), but the mechanisms underlying how GAS8-AS1 regulates PTC biology remain unclear. Here, we evaluated the molecular function of GAS8-AS1 in regulating autophagy in PTC cell lines.

METHODS

GAS8-AS1 was overexpressed and knocked down in PTC cell lines by transfecting with expression plasmids or short interfering RNAs (siRNAs). Cell proliferation was evaluated using the Cell Counting Kit-8 (CCK-8). qRT-PCR and western blot were used to determine changes in expression of autophagy-related genes. Autophagy was evaluated by immunofluorescence and transmission electron microscopy.

RESULTS

Relative GAS8-AS1 expression was lower in the PTC cell lines, TPC1 and BCPAP, compared to a normal thyroid cell line. Overexpression of GAS8-AS1 inhibited proliferation, significantly increased the ratio of LC3-II/LC3-I, and reduced p62 expression, whereas GAS8-AS1 knockdown demonstrated opposite effects. In GAS8-AS1 overexpressing cell lines, LC3 immunofluorescence staining demonstrated increased punctate aggregates of LC3 staining, and transmission electron microscopy revealed increased numbers of autophagosomes. Autophagy-related gene 5 (ATG5) was markedly upregulated by GAS8-AS1 overexpression and downregulated by GAS8-AS1 knockdown. Finally, silencing of ATG5 attenuated autophagy activation and rescued the inhibition of cell proliferation caused by GAS8-AS1.

CONCLUSIONS

In PTC cell lines, GAS8-AS1 inhibited proliferation, activated autophagy, and increased ATG5 expression. Downregulation of ATG5 reversed GAS8-AS1-mediated activation of autophagy leading to cell death, revealing a novel mechanism of the GAS8-AS1-ATG5 axis in PTC cell lines. This provided a new experimental basis to explore the effects of lncRNA on autophagy in the treatment of thyroid cancer.