Patients with incidentally detected thyroid cancer on screening have more favorable outcomes with better survival rates, suggests a study published in Endocrinology and Metabolism, a journal of the Korean Endocrine Society.¹

In this study, a research team from South Korea sought to compare the outcomes of incidental thyroid cancer (ITC) and non-incidental thyroid cancer (NITC) in patients to assess the impact of screening on the outcomes of thyroid cancer. A total of 9432 patients were recruited for the study. More than half of them (53.9%) had incidentally diagnosed thyroid cancer. For this they determined the prevalence of aggressive histologic features in the two cancers. The differences in the thyroid cancer-specific mortality and recurrence rates were also evaluated. They identified 14 studies to be included in the meta-analysis after a comprehensive search of Ovid-MEDLINE Embase, and the Cochrane Library databases from inception to September 2022.

Compared to NITC, patients with ITC were significantly less likely to have aggressive histological features with odds ratio (OR) of 0.46. They also had smaller tumor size with a mean difference of -7.9 mm between the two groups. The incidence of regional lymph node metastasis (OR 0.64) and distant metastasis (OR 0.42) was also lower. The risk of extrathyroidal extension was also lower in ITC patients. Patients with ITC were at significantly lower risk of recurrence of the disease compared to those with NITC (OR, 0.42). Thyroid cancer-specific mortality was also lower in this group (OR 0.46).

Current guidelines from various organizations like the US Preventive Services Task Force, American Cancer Society, American Thyroid Association, and the American Association of Clinical Endocrinologists, American College of Endocrinology, and Associazione Medici Endocrinologi do not recommend screening for thyroid cancer in asymptomatic persons. 

This study shows that patients with incidentally detected thyroid cancer had fewer unfavorable features such as aggressive histology, large tumor size, extrathyroidal extension and advanced TNM stage compared to those who had symptomatic thyroid cancer. They also had lower recurrence rates and increased survival rates indicating better prognosis. These findings establish the effectiveness and advantages of early detection of thyroid cancer by screening. “The ultimate goal of cancer screening, which generally aims to detect cancer at an early stage rather than to prevent cancer occurrence, is to reduce cancer-related mortality”, note the authors.

Reference

1. Moon S, et al. Lower thyroid cancer mortality in patients detected by screening: a meta-analysis. Endocrinol Metab (Seoul). 2023 Feb;38(1):93-103. doi: 10.3803/EnM.2023.1667.