Changes in Thyroid Cancer Incidence Post-2009 ATA Guidelines

What is the impact of the 2009 American Thyroid Association (ATA) thyroid cancer guidelines on incidence rates?

Bottom line
The rapid increase in thyroid cancer incidence rates over the past three decades has recently slowed, especially among small-sized cancers and women, which coincides with the 2009 ATA guideline revisions.

Background: The thyroid cancer incidence rate has tripled in the United States since the 1980s, especially among women and small-sized tumors. This trend has been attributed to increased detection due to the availability of ultrasound and fine-needle aspiration technology. In 2009, the ATA revised its management guidelines for well-differentiated thyroid nodules in favor of less aggressive diagnostic management, specifically in terms of criteria for fine-needle aspiration (FNA) biopsy. Previously, all sonographic findings of nodules >1.0 to 1.5 cm were confirmed indiscriminately by FNA. However, the ATA now cautions frugality, recommending against biopsy of subcentimeter nodules unless the patient has suspicious findings on clinical exam, strong risk factors on history, or imaging results suggestive of malignancy on ultrasound. The ATA now also recommends only a lobectomy rather than a near-total or total thyroidectomy for low-risk, unifocal, intrathyroidal PTC < 1.0 cm in size and decreased the recommendation rating for a prophylactic near-total or total thyroidectomy in indeterminate nodules. In addition, the guidelines only recommend a central and lateral compartment neck dissection in patients with PTC and suggest that a neck dissection may not be necessary in patients with small, noninvasive, clinically node-negative PTC treated with near-total or total thyroidectomy.

Synopsis: Cases of differentiated thyroid cancer diagnosed from 2000 to 2012 were analyzed from the National Cancer Institute Surveillance Epidemiology and End Results (SEER) program. Trends in incidence rates based on gender (males, females) and tumor size (< 1.0 cm, 1.0–2.9 cm, 3.0–3.9 cm, ≥ 4.0 cm) were analyzed using Joinpoint Regression and reported as the annual percentage change (APC). In total, 106,209 cases of differentiated thyroid cancer with known tumor size were diagnosed in the SEER 18 registries between 2000 and 2012. From 2000 to 2009, overall thyroid cancer incidence rates increased rapidly by approximately 8% per year in both sexes. Incidence rates increased across all tumor sizes, but especially in tumors 1.0 to 2.9 cm (men, APC = 7.7; women, APC = 7.8) and < 1.0 cm (men, APC = 7.8; women = 10.9) for both genders. Since 2009, the trend slowed in men (APC = 3.0) and women (APC = 2.8). The deceleration among females was confined to tumors smaller than 2.9 cm. Trends for all size groups in males remained constant from 2000 to 2012.