The incidence of thyroid carcinoma has been increasing worldwide. This is interpreted as an increase in the incidental detection of papillary thyroid microcarcinomas (PTMCs). However, mortality has not changed, suggesting overdiagnosis and overtreatment. Prospective clinical trials of active surveillance for low-risk PTMC (T1aN0M0) have been conducted in two Japanese institutions since the 1990s. Based on the favorable outcomes of these trials, active surveillance has been gradually adopted worldwide. A task force on the management of PTMC in adults organized by the Japan Thyroid Association therefore conducted a systematic review and has produced the present position paper based on the scientific evidence concerning active surveillance. This paper indicates evidence for the increased incidence of PTMC, favorable surgical outcomes for low-risk PTMC, recommended criteria for diagnosis using fine needle aspiration cytology, and evaluation of lymph node metastasis (LNM), extrathyroidal extension (ETE) and distant metastasis. Active surveillance has also been reported with a low incidence of disease progression and no subsequent recurrence or adverse events on survival if conversion surgery was performed at a slightly advanced stage. Active surveillance is a safe and valid strategy for PTMC, because it might preserve physical quality of life and reduce 10-year medical costs. However, some points should be noted when performing active surveillance. Immediate surgery is needed for PTMC showing high-risk features, such as clinical LNM, ETE or distant metastasis. Active surveillance should be performed under an appropriate medical team and should be continued for life.

甲状腺癌的发病率在全球范围内呈上升趋势。这被解释为偶然发现微小乳头状甲状腺癌 (PTMC) 的增加。然而，死亡率并没有改变，这表明过度诊断和过度治疗。自 1990 年代以来，两个日本机构已对低风险 PTMC (T1aN0M0) 进行主动监测的前瞻性临床试验。基于这些试验的良好结果，主动监测已在世界范围内逐步采用。因此，由日本甲状腺协会组织的成人 PTMC 管理工作组进行了系统评价，并根据有关主动监测的科学证据制定了本立场文件。本文指出了 PTMC 发病率增加的证据，低风险 PTMC 的良好手术结果，使用细针抽吸细胞学诊断的推荐标准，以及淋巴结转移 (LNM)、甲状腺外扩展 (ETE) 和远处转移的评估。据报道，如果在稍晚期进行中转手术，则主动监测的疾病进展发生率较低，并且没有随后的复发或生存不良事件。主动监测对 PTMC 来说是一种安全有效的策略，因为它可以保持身体生活质量并降低 10 年的医疗费用。但是，在进行主动监测时应注意一些要点。显示高风险特征的 PTMC 需要立即手术，例如临床 LNM、ETE 或远处转移。