Analysis of the clonal origin and differences in the biological behavior of multifocal papillary thyroid carcinoma

Abstract

Papillary thyroid carcinoma (PTC) exhibits a trend of multifocal growth. However, the clonal origin of multiple cancer foci in the thyroid gland remains an issue of ongoing debate. In order to investigate the clonal origin and biological behavior differences of multifocal PTC (MPTC) from a unique perspective, a combination of dual gene and dual protein detection methods was used. The present study included 52 patients with MPTC. Immunohistochemical staining was used to assess the expression of v-raf murine sarcoma viral oncogene homolog B1 (BRAF) and telomerase reverse transcriptase (TERT) proteins, while quantitative PCR and Sanger sequencing were used to identify BRAF and TERT gene mutations. Based on the results, MPTC cases were classified into two clonal origins, namely intraglandular metastatic (71.2%) and independent multicentric origin (28.8%). BRAF protein expression and BRAF gene mutation were significantly higher in the intraglandular metastasis group than in the multicentric cancer group. However, no significant differences in TERT protein expression and TERT gene mutation were observed between the two groups. Sex, central lymph node metastasis rate, Hashimoto's thyroiditis and tumor distribution laterality were not found to differ significantly between the two groups. However, significant differences were detected in age at initial diagnosis, lateral cervical lymph node metastasis rate, tumor capsule invasion rate and maximum tumor diameter. The study found that MPTC predominantly occurs due to intraglandular metastasis, which is associated with stronger tumor invasiveness than cancer foci with multiple independent origins, as it is more likely to exhibit pathogenic gene mutations and abnormal protein expression, cervical lymph node metastasis and capsule invasion. Therefore, it is recommended that the surgical approaches and follow-up strategies for intraglandular metastatic MPTC should be aggressive and individualized.

Keywords: biological behavior; clonal origin; multifocal papillary thyroid carcinoma; telomerase reverse transcriptase; v-raf murine sarcoma viral oncogene homolog B1.

Figure 1.

Histology of individual multifocal papillary thyroid carcinoma samples. Representative images of (A) BRAF protein-positive, (B) BRAF protein-negative, (C) TERT protein-positive and (D) TERT protein-negative samples. Magnification, ×40. BRAF, v-raf murine sarcoma viral oncogene homolog B1; TERT, telomerase reverse transcriptase.

Figure 2.

BRAF V600E mutation in multifocal papillary thyroid carcinoma. Representative (A) BRAF V600E mutant and (B) wild-type amplification plots generated using quantitative PCR. The red marking represents the threshold line. BRAF, v-raf murine sarcoma viral oncogene homolog B1; BRAF-IC, BRAF internal reference gene detection curve; BRAF-W, BRAF V600E wild-type gene detection curve; BRAF-M, BRAF V600E mutation gene detection curve; DRn, change in relative fluorescence normalized.

Figure 3.

TERT promoter mutation in multifocal papillary thyroid carcinoma. (A) TERT promoter mutation and (B) TERT promoter wild-type detection spectra generated using Sanger sequencing. The red marking indicates the gene locus mutation and the blue marking indicates no mutation in the gene locus. TERT, telomerase reverse transcriptase.

Figure 4.

Clonal origin of multifocal papillary thyroid carcinoma. Red represents the intraglandular metastatic cancer group, and blue represents the multicentric cancer group.