Background and purpose: The incidence of thyroid cancer (TC) is increasing worldwide. However

there were some differences among different regions. The purpose of this study was to investigate the incidence trends and clinicopathological characteristics of TC in Qingdao

a typical eastern coastal city

and to analyze the change in etiological spectrum of surgical thyroid diseases in recent years. Methods: A total of 2 251 patients who underwent thyroidec

tomy in 2014 due to thyroid nodules at the Affiliated Hospital of Qingdao University were retrospectively reviewed. The clinicopathological characteristics were further analyzed among 1 306 patients with TC and compared with the corresponding data from the Surveillance Epidemiology and End Results (SEER) database as well as previous data from this hospital. Results: With the increasing number of thyroidectomy in Qingdao

there was also an increase in the proportion of TC in patients after thyroidectomy

from 34.8% in 2010 to 59.0% in 2014. Among those with TC

the male-to-female ratio was 1∶2.80

with a relatively high incidence among 20-54 year-old adults

who were younger than those reported in terms of distribution of age in SEER database (U=2 289

P=0.000). About 50.2% of the TC patients were overweight or obese

78.2% TC patients had only asymptomatic nodules detected by ultrasound at initial diagnosis

while 16.6% had visible or palpable thyroid nodules. Only 5.2% presented hoarseness or other repression symptoms. Micro-carcinoma accounted for 61.7% of TC in 2014 at this hospital

which was significantly higher than the proportion in 2010 (37.7%). Lymph node involvement was significantly more frequent at this hospital than in SEER database (49.5% vs 26.0%

χ

2

=11.806

P=0.001). Even among patients with micro-carcinoma

31.3% already presented lymph node metastases. The proportions of papillary

follicular

medullary and anaplastic carcinoma were 97.5%

1.1%

1.0% and 0.5%

respectively

among which the percentage of papillary carcinoma was higher than that in SEER database (U=4 654.5

P=0.055). Conclusion: There was an increase in the number of thyroidectomy in Qingdao

and the preoperative diagnostic accuracy of TC in this area kept rising. The incidence of TC was relatively high in a younger population

with more common lymph node involvements and an overweight trend. The increasing proportion of micro-carcinoma might be related to the popularization of health examination. However

the frequent

lymph node metastasis in patients with micro-carcinoma is an important indicator of the invasive behavior of micro-carcinoma

which should not be overlooked.