Background: The question of how to manage patients with low-risk papillary thyroid microcarcinoma (PTMC; T1aN0M0) has recently become an important clinical issue. Two Japanese centers have conducted prospective clinical trials of active surveillance (AS) for low-risk PTMC since the 1990s, reporting favorable outcomes. This policy has thus seen gradual adoption worldwide to avoid overtreatment. Not all PTMCs are suitable for AS, however, and many physicians still hesitate to apply the management policy in daily clinical practice. A task force on management for PTMC created by the Japan Association of Endocrine Surgery collected and analyzed bibliographic evidence and has produced the present consensus statements regarding indications and concrete strategies for AS to facilitate the management of adult patients diagnosed with low-risk PTMC. Summary: These statements provide indications for AS in adult patients with T1aN0M0 low-risk PTMC. PTMCs with clinical lymph node metastasis, distant metastasis, recurrent laryngeal nerve (RLN) paralysis due to carcinoma invasion, or protrusion into the tracheal lumen warrant immediate surgery. Tumors suspected of aggressive subtypes on cytology are recommended for immediate surgery. Immediate surgery is also recommended for tumors adherent to the trachea or located along the course of the RLN. Practical strategies include diagnosis, decision-making, follow-up, and monitoring related to the implementation of AS. The rate of low-risk PTMC progression is lower in older patients. However, we recommend continuing AS as long as circumstances permit. Future tasks in optimizing management for low-risk PTMC are also described, including molecular markers and patient-reported outcomes. Conclusions: An appropriate multidisciplinary team is necessary to accurately evaluate primary tumors and lymph nodes at the beginning of and during AS, and to adequately reach a shared-decision with individual patients. If appropriately applied, AS of low-risk PTMC is a safe management strategy offering favorable outcomes and preserves quality of life at low cost.

PTEG with RFB is as safe as PEG and is simple and less invasive. It can be used in some cases for which PEG is contraindicated.

This study is an initial report indicating that the risk of PTMC enlargement might increase during pregnancy. PTMC should be carefully followed-up for possible disease aggravation during pregnancy. Even if a PTMC enlarges during pregnancy, the patient's prognosis will probably not worsen.

Background: We previously reported that the Ki-67 labeling index (LI) in primary tumors and the thyroglobulin (Tg)-doubling time (DT) were potent prognostic indicators in patients with papillary thyroid carcinoma (PTC). Objectives: To elucidate the relationship between these two factors. Methods: A total of 390 patients with PTC who underwent total thyroidectomy between 1998 and 2004 and in whom the Tg-DT was calculated were enrolled. We determined the Ki-67 LI in primary tumors and compared these values with the patients' clinicopathological factors, postoperative Tg status, Tg-DT, and prognosis. Tg status was categorized by postoperative serum Tg values: biochemically persistent disease (BPD), equivocal state, and biochemical remission. Results: The Ki-67 LI was ≤5% in 312 patients (80%), 5%-10% in 48 patients (12%), and >10% in 30 patients (8%). Ki-67 LI was significantly associated with BPD (p < 0.0001). The proportion of BPD patients increased with the higher Ki-67 LI category: 24, 67, and 87%, respectively. The Ki-67 LI had a significant inverse correlation with the Tg-DT (Spearman's ρ = −0.5267, p < 0.0001). Of the 378 patients without distant metastasis at surgery, 68 patients had recurrence, and 6 of the 390 patients died of PTC during the follow-up (mean 88 months). On multivariate analyses, the Ki-67 LI remained an independent predictor of disease-free survival and disease-specific survival when Tg-DT and Tg status were excluded from the analyses. Conclusions: Evaluation of the Ki-67 LI in primary tumors may allow the prediction of the postoperative Tg status, Tg-DT and prognosis of patients with PTC.

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.