Endpoints for screening thyroid cancer in the Republic of Korea: thyroid specialists’ perspectives

Abstract

Cancer screening is aimed primarily at reducing deaths from the specific cancer. Thyroid-specific cancer mortality may be the most ambitious endpoint for obtaining estimates of screening effect. Numerous observations have accumulated over the years, indicating that thyroid cancer mortality endpoint has been difficult to study and is confounded by population heterogeneity, provision of randomization, and requirement of large cohorts with sufficiently long follow-up due to the excellent prognosis of the cancer. Accordingly, it may be important to reconsider how to best measure thyroid cancer screening efficacy. Recommendations against thyroid cancer screening should be based upon trials designed to evaluate its effectiveness not only in significant reduction in cancer mortality, but also of other distinct endpoints. It is desirable to evaluate derivative endpoints that can reliably predict reductions in mortality. The term "derivative" means a variable that is related to the true endpoint and is likely to be observable before the primary endpoint. Derivative endpoints may include thyroid cancer incidence, the proportion of early-stage tumors detected, more treatable stage, the identification of small tumors (to maintain in observation), decrease in the number of people who develop metastatic disease, the increased chance of lesser extent surgery, and the application of minimally invasive approaches, as well as no need for lifelong thyroid replacement therapy, a consistent follow-up, low-dose or no RAI administration and risk factor assessments where case findings should be continuous. The Korean guidelines for thyroid cancer national-level screening were published by a relevant group of multidisciplinary thyroid experts. It was concluded that the evidence is insufficient to balance the benefits and harms of thyroid cancer screening. However, the paper seems to raise the necessary investments in future research and demand a complete analysis for derivative endpoints, and offer screening participants with complete information necessary to make decisions that will provide them with the most value when a small thyroid cancer is screen-identified.

Ultrasound Risk Categories for Thyroid Nodules and Cytology Results: A Single Institution’s Experience after the Adoption of the 2016 Update of Medical Guidelines by the American Association of Clinical Endocrinologists and Associazione Medici Endocrinologi

“…It is plausible that when following these guidelines, the diagnosis of malignancy is delayed in a nonnegligible number of patients if FNA is not done until the nodule is ≥20 mm. Given that the mortality rate is not reduced if there is cytologic assessment of intermediate risk nodules <20 mm, previous findings strongly support that an earlier diagnosis is associated with less lymph node involvement, extrathyroidal extension, and lower recurrence rates [22–24]. …”

Is advocacy for active surveillance over definitive intervention in papillary thyroid microcarcinoma applicable to European patients?

“…In the last two decades there has been a significant increase in the number of small papillary thyroid carcinomas worldwide (1).…”

“…In addition to the question of the cause of this phenomenon, especially its therapeutic consequence is the focus of discussion (1).…”

“…In a study, 2,153 patients with low-risk PMC, who were either primarily active surveillance [1,179] or primarily operated [974] between 2005 and 2013 at the Kuma Hospital in Japan, were analyzed (2).…”

“…The present retrospective studies are considered to be sufficient basis for the fact that patients with low risk PMC can be offered a primary observational procedure in compliance with certain criteria, since the oncological results are indistinguishable and the operative morbidity during primary observation is significantly lower (1).…”