Radioactive iodine treatment for differentiated thyroid carcinoma in Japan

Outcomes of Patients with an Intermediate-Risk Group According to the Japanese Risk Classification of Papillary Thyroid Carcinoma

BACKGROUND

The management of intermediate-risk group of papillary thyroid cancer (PTC) is still vague, particularly regarding whether or not total thyroidectomy, postoperative radioactive iodine ablation (RAI-a), and postoperative TSH suppression are mandatory.

METHODS

This retrospective study evaluated 680 PTC patients from 2010 to 2017, who were classified into the three risk groups as low, intermediate, and high-risk groups according to the criteria of the Japanese Association of Endocrine Surgeons (JAES) 2010 and underwent surgery according to the JAES guidelines. We retrospectively collected patient data for analyses of disease-free survivals in the intermediate-risk group patients.

RESULTS

We performed surgery on 680 PTC patients from 2010 to 2017. Of them, 297 were classified as the intermediate-risk group. DFS was not statistically significantly different in patients with/without total thyroidectomy and postoperative TSH suppression therapy. For RAI-a, DFS (95% confidence interval) at 3, 5, and 8 years were 93.2% (84.6 ~ 97.2), 81.6% (68,3 ~ 90.2), and 70.7% (51.4 ~ 84.6) in patients with postoperative RAI-a and 100%, 100%, and 100% in patients without postoperative RAI-a after total thyroidectomy, respectively. DFS of patients without RAI-a was superior to those with RAI-a (P < 0.0004). Multivariable analysis by stepwise selection method revealed that postoperative RAI-a was a risk factor with a hazard ratio of 5.69. (95% CI 1.998-16.21) (P = 0.001131).

CONCLUSIONS

Our study did not show the efficacy of RAI-a in patients with intermediate-risk PTC. This study implies that judging the efficacy of adjuvant therapy such as RAI or TSh suppression in intermediate-risk patients is difficult.

Radioactive iodine treatment of papillary thyroid carcinoma in Japan

We have a unique history of using radioactive iodine (RAI) therapy and surgical treatment for thyroid cancer in Japan. Less than total thyroidectomy without RAI therapy was the most common management of papillary thyroid carcinoma (PTC) in the past. Limited availability of dedicated facilities for the RAI administration due to the strict regulations and insufficient coverage of the expenses were the major reasons that impacted on the management decisions. Following the publication of the Japanese clinical practice guidelines for thyroid tumors in 2010, the risk-adapted approach has become a standard where the high-risk and selected intermediate-risk PTC patients undergo total thyroidectomy followed by RAI therapy and thyrotropin suppression therapy. We are on the shoulders of pioneers who made every effort to bring the interventions closer to an ideal environment for patients. Armed with the revised clinical practice guidelines 2018 and devised inpatient/outpatient RAI therapy, Japanese physicians are ready to proceed to more rational management that would improve patients' outcomes. Directions for the future include further advancement of relevant clinical research to fill the gaps between current evidence and recommendations in the guidelines, and obtaining approval for high-dose RAI therapy on an outpatient basis to improve its effectiveness in both adjuvant and treatment settings.

Radioactive iodine (131I) therapy for differentiated thyroid cancer in Japan: current issues with historical review and future perspective

Radioactive iodine (RAI, (131)I) has been used as a therapeutic agent for differentiated thyroid cancer (DTC) with over 50 years of history. Recently, it is now attracting attention in medical fields as one of the molecular targeting therapies, which is known as targeted radionuclide therapy. Radioactive iodine therapy (RIT) for DTC, however, is now at stake in Japan, because Japan is confronting several problems, including the recent occurrence of the Great East Japan Disaster (GEJD) in March 2011. RIT for DTC is strictly limited in Japan and requires hospitalization. Because of strict regulations, severe lack of medical facilities for RIT has become one of the most important medical problems, which results in prolonged waiting time for Japanese patients with DTC, including those with distant metastasis, who wish to receive RIT immediately. This situation is also due to various other factors, such as prolonged economic recession, super-aging society, and subsequent rapidly changing medical environment. In addition, due to the experience of atomic bombings in Hiroshima and Nagasaki, Japanese people have strong feeling of "radiophobia". There is fear that GEJD and related radiation contamination may worsen this feeling, which might be reflected in more severe regulation of RIT. To overcome these difficulties, it is essential to collect and disclose all information about the circumstances around this therapy in Japan. In this review, we would like to look at this therapy through several lenses, including historical, cultural, medical, and socio-economic points of view. We believe that clarifying the problems is sure to lead to the resolution of this complicated situation. We have also included several recommendations for future improvements.