Total tumor diameter: the neglected value in papillary thyroid microcarcinoma

Area of Science:

• Oncology
• Pathology
• Surgical Oncology

Background:

• Papillary thyroid carcinoma (PTC) can present as multifocal tumors, particularly in micro-PTC.
• Assessing only the largest tumor may misrepresent the overall tumor burden and aggressiveness.
• Total tumor diameter (TTD) offers a more comprehensive measure for multifocal PTC.

Purpose of the Study:

• To investigate the impact of total tumor diameter (TTD) on the clinicopathological features of micro-PTC.
• To determine if TTD provides a better assessment of tumor aggressiveness in multifocal micro-PTC compared to unifocal micro-PTC.

Main Methods:

• Retrospective analysis of data from 442 patients who underwent thyroidectomy for PTC.
• Classification of patients into subgroups based on tumor multifocality and TTD.
• Statistical analysis to compare clinicopathological features across different tumor groups.

Main Results:

• Multifocality was present in 26.9% of patients.
• Multifocal tumors showed significantly higher TTD (>1 cm) and extrathyroidal extension (ETE) compared to unifocal tumors.
• Multifocal micro-PTC with TTD >1 cm exhibited higher rates of ETE, central lymph node metastasis (CLNM), and lateral lymph node metastasis (LLNM) than unifocal or smaller multifocal tumors.
• The risk of CLNM was over twice as high in multifocal micro-PTC with TTD >1 cm compared to unifocal micro-PTC.

Conclusions:

• Total tumor diameter (TTD) is a valuable metric for assessing the aggressiveness of multifocal micro-PTC.
• Multifocal micro-PTC with a TTD greater than 1 cm demonstrates increased aggressiveness, comparable to larger PTC.
• These findings highlight the importance of considering TTD in multifocal micro-PTC for accurate prognostication and treatment planning.