Management of low-risk papillary thyroid carcinoma: Unique conventional policy in Japan and our efforts to improve the level of evidence

Abstract

Papillary thyroid carcinoma (PTC) accounts for over 90% of all thyroid cancers in Japan. The majority of patients with PTC are categorized into a low-risk group according to the recent risk-group classification schemes, and they have excellent outcomes. Several management guidelines for thyroid cancers have been published in Western countries. However, the optimal therapeutic options for PTC remain controversial and high-level clinical evidence to resolve the issues is lacking. Moreover, socioeconomic differences in medical care exist; therefore, conventional policies for the treatment of PTC have been different between Japan and other countries. This report reviews the controversy in the treatment of PTC regarding the initial surgery, postoperative adjuvant therapies, and methods of surveillance. This review focuses on the unique policy in Japan preferring to treat patients with low-risk PTC by a less-than-total thyroidectomy without adjuvant therapies rather than a total thyroidectomy with radioactive iodine, in an attempt to maintain patients' quality of life. In addition, the institutional efforts to improve the level of evidence for the management of PTC are introduced, such as a randomized controlled trial for the effect of thyrotropin suppression therapy, a prospective study for selective lymph node dissection based on preoperative ultrasonography, and a prospective nonsurgical observation trial for asymptomatic papillary microcarcinoma.