Progression of solitary and multifocal papillary thyroid carcinoma- a retrospective study of 368 patients

Background Papillary thyroid carcinoma （PTC） represents one of the most frequent endocrine malignancies. Several factors have been found to be involved in determining the outcome of treatment for patients with PTC. Large tumor size, diagnosis at an early age, extra-thyroidal invasion, aggressive histological variants, and distant metastases are the most important determinants of a poor outcome. BRAF^V600E mutation has been found to be a major genetic alteration in PTC. This study aimed to evaluate progression in patients with multifocal and solitary PTC. Methods We performed a retrospective study to analyze 368 patients with PTC who underwent surgery, including 282 patients with solitary PTC and 86 patients with multifocal PTC. The status ofBRAF^V600E mutation in all tumor foci from multifocal PTC was detected. Results Our study suggested that multifocal PTC was more related to lymph node metastasis and vascular invasion than solitary PTC. However, the distant metastasis rate and 10-year survival rate showed no difference between these two groups. The number of tumor loci did not affect progression of disease in multifocal PTC patients. Lymph node metastasis in multifocal PTC patients was associated with larger tumors, diagnosis at early stage, and extra-thyroidal invasion. Conclusion The status of BRAF^V600Emutation was more frequent in multifocal PTC patients with lymph node metastasis and diagnosis at later age.