Should small papillary thyroid cancer be observed? A population-based study

Abstract

Background: Some centers have advocated selecting patients with small papillary thyroid cancer (PTC) to undergo active surveillance without surgical treatment. The objectives of the current study were to analyze thyroid cancer (TC)-related mortality in a population-based cohort and to determine the impact of small PTCs (defined as tumors ≤ 2 cm in greatest dimension) on TC-related mortality.

Methods: Data on patients with TC of follicular cell origin from the National Cancer Institute's Surveillance, Epidemiology, and End Results 17 Registries database (1988-2007) were used to analyze the characteristics of PTCs ≤ 2 cm in patients who died from TC-related causes. The effects of clinical features on disease-specific survival were analyzed.

Results: Over the 20-year study period, the rate of TC-related mortality was 2.8% (n = 1753 of 61,523 patients). Of the patients who died from TC-related causes, 38% had PTC, 10% had follicular TC, and 31.3% had anaplastic TC. PTCs ≤ 2 cm accounted for 12.3% of TC-related mortalities. Compared with patients who did not experience TC-related mortality from PTCs ≤ 2 cm, there were significantly higher rates of men (30% vs 17%; P < .01), patients aged ≥ 45 years (92% vs 52%; P < .01), tumors measuring >1 cm (59% vs 46%; P < .01), extrathyroid extension (41% vs 11%; P < .01), lymph node metastases (77% vs 28%; P < .01), and distant metastases (31% vs 1%; P < .01) among the patients who died from PTCs ≤ 2 cm. Independent risk factors for death from PTCs ≤ 2 cm included age ≥ 45 years, lymph node and distant metastases, extrathyroid extension, and undergoing less than thyroid lobectomy.

Conclusions: Because 12.3% of patients who experienced TC-related deaths had PTCs ≤ 2 cm despite undergoing thyroidectomy, the current results indicate that nonoperative management for patients who have PTCs ≤ 2 cm should be used with caution. Patients aged ≥ 45 years with PTCs ≤ 2 cm should undergo thyroidectomy.

Keywords: Surveillance, Epidemiology, and End Results Program; cancer-specific survival; mortality; prognostic factor; thyroid cancer.

Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Figures

Figure 1

Thyroid cancer–related mortality (n = 1,753) in the SEER program from 1988 to 2007 by histology.

Figure 2

A, The incidence of thyroid cancer of follicular cell origin in the SEER program, from 1988 to 2007, by year of diagnosis. Blue bars represent PTMC. Red bars represent PTC with tumors ≥ 1–2 cm in size. B, The rates of thyroid cancer–related mortality (percent of number of annual deaths by total number of cases diagnosed each year) by the year of diagnosis. Blue line represents overall TC-mortality rate by year. Red line represents TC-mortality rate of patients with PTC ≤ 2 cm. C, Estimated disease-specific survival of patients with thyroid cancer of follicular cell origin by decade of diagnosis. Analysis was performed using a Kaplan–Meier estimator with a log-rank (Mantel–Cox) test.

Figure 2

A, The incidence of thyroid cancer of follicular cell origin in the SEER program, from 1988 to 2007, by year of diagnosis. Blue bars represent PTMC. Red bars represent PTC with tumors ≥ 1–2 cm in size. B, The rates of thyroid cancer–related mortality (percent of number of annual deaths by total number of cases diagnosed each year) by the year of diagnosis. Blue line represents overall TC-mortality rate by year. Red line represents TC-mortality rate of patients with PTC ≤ 2 cm. C, Estimated disease-specific survival of patients with thyroid cancer of follicular cell origin by decade of diagnosis. Analysis was performed using a Kaplan–Meier estimator with a log-rank (Mantel–Cox) test.

Figure 2

A, The incidence of thyroid cancer of follicular cell origin in the SEER program, from 1988 to 2007, by year of diagnosis. Blue bars represent PTMC. Red bars represent PTC with tumors ≥ 1–2 cm in size. B, The rates of thyroid cancer–related mortality (percent of number of annual deaths by total number of cases diagnosed each year) by the year of diagnosis. Blue line represents overall TC-mortality rate by year. Red line represents TC-mortality rate of patients with PTC ≤ 2 cm. C, Estimated disease-specific survival of patients with thyroid cancer of follicular cell origin by decade of diagnosis. Analysis was performed using a Kaplan–Meier estimator with a log-rank (Mantel–Cox) test.