Size Increment During Surveillance in Papillary Thyroid Cancer: Evidence Synthesis and Dose-Response Meta-Analysis

Differentiated thyroid cancer has become a prevalent malignant tumor, particularly papillary thyroid carcinoma (PTC), constituting over 90% of cases. Most PTC lesions are asymptomatic and remain subclinical throughout life, and active surveillance is now being used to monitor the progression of these lesions and intervene when appropriate. This evidence synthesis aims to assess PTC progression in size over time during active surveillance in terms of PTC tumor size progression to or beyond 3 mm during the surveillance period.

A dose-response meta-analysis was conducted using the robust error meta-regression method, using time as the "dose" and cumulative progression (%) was assessed. A comprehensive literature review was done using PubMed/MEDLINE and EMBASE from inception till August 2024.

A total of 21 studies from 7 different countries, including 14 648 participants, were included. Incident progression at 2 years of follow-up was 1%, and this increased linearly to 12% at 20 years of follow-up.

It was concluded that progression over the threshold increases linearly over time at approximately less than 1% per year. Therefore, size progression beyond the threshold occurs in a minority and in less than one eighth of subjects by two decades of follow-up.