Risk Factors for Tumor Size Increase During Active Surveillance of Papillary Thyroid Cancer: Meta-Analysis and Systematic Review

Abstract

Background and Objectives The purpose of this study was to systematically review literatures on active surveillance for low-risk differentiated thyroid cancer, and to evaluate risk factors for tumor size increase during active surveillance.Subjects and Method We conducted a systematic review and a meta-analysis of studies reporting on tumor growth during active surveillance of papillary thyroid cancer. Using the MEDLINE and EMBASE databases, we searched studies published from the inception of database to December 2020. Studies were included if reported on at least one clinical risk parameter in addition to reporting on the change in tumor size during active surveillance.Results Out of 33 studies screened, seven were included in the meta-analysis. The odds ratio of a temporal size increase of more than 3 mm in papillary thyroid cancer was 0.011 person-years (95% confidence interval [CI]: 0.009 to 0.013). The odds ratio of lymph node metastasis was 0.002 person-years (95% CI: 0.001 to 0.003). Younger age was a significant risk factor for tumor growth during active surveillance, with a standardized median difference of -0.63 (95% CI: -1.00 to -0.27). In the three studies that evaluated the association of thyroid-stimulating hormone levels and tumor size, the results were contradictory.Conclusion Active surveillance may be used more cautiously for younger patients.