Nationwide cohort study on the epidemiology and survival outcomes of thyroid cancer

Abstract

In the past three decades, the thyroid cancer incidence has surged globally. Herein, the Taiwan National Health Insurance database was used to identify thyroid cancer patients and to estimate the prevalence and incidence of thyroid cancer during 1997-2012. The Taiwan Cancer Registry and the National Death Registry databases were crosslinked to obtain information on the histological subtypes and survival rates. Joinpoint regression analysis was used for estimating the average annual percentage changes (APCs) in prevalence, incidence, and survival. The age-standardized incidence of thyroid cancer increased from 5.66 per 100,000 person-years in 1997 to 12.30 per 100,000 person-years in 2012, with an average APC of 5.1 (6.9 in males, 4.6 in females). Thyroid cancer was more prevalent in patients with high socioeconomic status and in urban areas. Papillary carcinoma was the most abundant subtype, with a 2.9-fold increase of incident cases noted during 1998-2012 (from 80.6% to 89.8% of all cases). Among the different treatments, partial thyroidectomy increased the most (average APC, 17.3). The overall survival rates by sex and subtype remained stable over time, with 5-year survival rates of 90.2% in 1997 and 92.4% in 2010. In conclusion, 2.2- and 4.2-fold increases in the incidence and prevalence of thyroid cancer, respectively, were observed during 1997-2012 in Taiwan. The surging incidence of thyroid cancer but stable survival rates, and mainly increased in the papillary subtype, altogether imply enhanced detection of subclinical lesions. A true increase due to environmental carcinogens might also be responsible, but warrant further investigations.

Keywords: National Health Insurance; Taiwan Cancer Registry; epidemiology; survival outcome; thyroid cancer.

Figure 1. Geographic variations in the prevalence and incidence of thyroid cancer in Taiwan in 1997 and 2012, and their associations with the sites of nuclear power plants in Taiwan

Figure 2

Differences by sex in the trends of (A) standardized prevalence and (B) standardized incidence of thyroid cancer in Taiwan between 1997 and 2012. (Red: female, green: total, blue: male.)

Figure 2

Differences by sex in the trends of (A) standardized prevalence and (B) standardized incidence of thyroid cancer in Taiwan between 1997 and 2012. (Red: female, green: total, blue: male.)

Figure 3

Differences by sex in the trends of (A) age-specific prevalence and (B) age-specific incidence of thyroid cancer in Taiwan between 1997 and 2012. (Red: female, blue: male.)

Figure 3

Differences by sex in the trends of (A) age-specific prevalence and (B) age-specific incidence of thyroid cancer in Taiwan between 1997 and 2012. (Red: female, blue: male.)

Figure 4. Secular trends of the incidence cases of different thyroid cancer subtypes in Taiwan between 1998 and 2012

(Red: papillary thyroid carcinoma, yellow: follicular thyroid carcinoma, blue: medullary thyroid carcinoma, green: anaplastic thyroid carcinoma, purple: other types.)

Figure 5

The percentages of different thyroid cancer subtypes in Taiwan in (A) 1998 and (B) 2012.

Figure 6. Secular trends of the numbers of different treatment procedures for thyroid cancer in Taiwan between 1997 and 2011

(Dotted line: the incidence cases at that specific year, orange: I-131 ablation, red: total thyroidectomy, yellow: partial thyroidectomy, green: lymph node dissection, blue: external beam radiotherapy, purple: chemotherapy.)

Figure 6. Secular trends of the numbers of different treatment procedures for thyroid cancer in Taiwan between 1997 and 2011

(Dotted line: the incidence cases at that specific year, orange: I-131 ablation, red: total thyroidectomy, yellow: partial thyroidectomy, green: lymph node dissection, blue: external beam radiotherapy, purple: chemotherapy.)

Figure 7

Secular trends of the one-, two-, and five-year survival rates of thyroid cancer in (A) female and (B) male patients in Taiwan from 1997 to 2012. (Blue: 1-year survival rate, red: 2-year survival rate, green: 5-year survival rate.)

Figure 8

Secular trends of the one-, two-, and five-year survival rates of thyroid cancer in patients with (A) Charlson Comorbidity Index (CCI) ≤ 3; (B) CCI ≥ 4 in Taiwan from 1997 to 2012. (Blue: 1-year survival rate, red: 2-year survival rate, green: 5-year survival rate.)