The recent prevalence of ultrasound-guided fine-needle aspiration biopsy has resulted in a marked increase in the number of patients with papillary microcarcinoma (maximum diameter, ≤ 10 mm) of the thyroid detected by this sophisticated tool. On the other hand, it is debatable whether patients with papillary microcarcinoma should always undergo surgery after diagnosis, because a high incidence of occult papillary carcinoma has been observed in autopsy studies. Thus, we proposed observation without surgical therapy as a treatment option in 732 patients diagnosed with papillary microcarcinoma by the above technique from 1993 to 2001. One hundred sixty-two patients chose observation and were classified as the observation group. During the follow-up period for patients in the observation group, more than 70% of tumors either did not change or decreased in size compared to their initial size at diagnosis. They enlarged by more than 10 mm in 10.2%, and lymph node metastasis in the lateral compartments appeared in only 1.2% of patients during follow-up. On the other hand, 570 patients chose surgical treatment at diagnosis and 56 patients in the observation group who underwent surgery after a period of follow-up were classified as the surgical treatment group. Of these 626 patients, lymph node dissection was performed in 594 patients, and metastasis was confirmed histologically in 50.5%. Multiple tumor formation was seen in 42.8% of patients. In this group, the rate of recurrence was 2.7% at 5 years and 5.0% at 8 years after surgery. Our preliminary data suggest that papillary microcarcinomas do not frequently become clinically apparent, and that patients can choose observation while their tumors are not progressing, although they are pathologically multifocal and involve lymph nodes in high incidence.

Introduction: Papillary thyroid carcinoma (PTC) generally shows an excellent prognosis except in cases with aggressive backgrounds or clinicopathological features. Although the cause‐specific survival (CSS) of PTC patients has been extensively investigated, the overall survival (OS) of these patients is unclear. We herein investigated both the OS and CSS of a large PTC patient series.Materials and methods: We enrolled 5897 PTC patients who underwent initial surgery between 1987 and 2005 (658 males and 5339 females; median age 51 years). Their median postoperative follow‐up period was 177 months. Univariate and multivariate analyses for OS and CSS assessed the effects of gender, older age (≥55 years), distant metastasis at diagnosis (M1), significant extrathyroid extension, tumor size (cutoffs 2 and 4 cm), large node metastasis (N ≥ 3 cm), and extranodal tumor extension.Results: To date, 387 patients (7%) in this series have died from various causes, including 117 (2%) due to PTC. The 10‐, 15‐, and 20‐year OS rates are 97, 95, and 90%, respectively. Older age and M1 were important prognostic factors for OS and CSS. Older age was a more significant factor than M1 for OS and vice versa for CSS. In the older patients, M1 was a prominent prognostic factor for both OS and CSS. In the young patients, M1 had less prognostic impact than in the older patients, and the prognostic values of M1 and N ≥ 3 cm for OS and CSS were identical and similar, respectively.Conclusions: The most important prognostic value for OS was patient age, indicating that PTC is generally indolent. However, the control of distant metastasis in older patients remains a future challenge in order to further improve their OS and CSS. PTC of ≥3 cm in young patients should be carefully followed, even in the absence of metastases, and these patients should undergo aggressive therapies for recurrent lesions and metastases.