Active surveillance of low-risk papillary thyroid microcarcinomas in Japan and other countries: a review

Introduction: Active surveillance of low-risk papillary thyroid microcarcinomas (PTMCs) was initiated in Japan in 1993 and has since been adopted in many countries, especially after its approval by the American Thyroid Association in 2015.Areas covered: We performed a literature review in Medline/PubMed to identify studies that used active surveillance for PTMCs. Moreover, we performed a literature review about the increased incidence of thyroid microcarcinomas in relation to the relative stability of deaths due to thyroid carcinomas.Expert opinion: No patients showed life-threatening metastasis/recurrence or died of thyroid carcinoma during active surveillance or after conversion surgery following PTMC progression. Thus, active surveillance should be the first-line management of PTMCs without high-risk features. In the future, molecular testing of actively growing PTMCs using cytology specimens could be useful to guide the treatment plan.