Features and trends of thyroid cancer in patients with thyroidectomies in Beijing, China between 1994 and 2015: a retrospective study.

Objectives This study aims to summarise the features and trends of thyroid carcinoma in the past two decades in China. Design, setting and participants Clinical data obtained from 10 798 patients treated by thyroidectomy from 1994 to 2015 at the Department of General Surgery of the People's Liberation Army General Hospital, Beijing, China were retrospectively analysed. Outcome measures Incidence and histopathological features of thyroid cancer were compared and the risk factors for local lymph node metastasis analysed. Results Our data indicated a significant increase in the detection of thyroid cancer (from 16.8% to 69.8%, p< 0.01). Among the 5235 thyroid cancer cases, papillary thyroid carcinoma (PTC) was the most common histotype, accounting for 95.1% of all malignancies over the 22-year period. Among the 4979 PTCs, micro-PTCs (mPTC) with the largest diameter <= 10 mm has gradually become the dominant form, and its percentage in PTCs has increased from 13.3% in the biennial period of 1994-1995 to 51.2% in 2010-2011. Furthermore, the size of the tumour has decreased significantly from 2.3 +/- 1.1 cm in 1994 to 1.2 +/- 0.9 cm in the largest diameter (p< 0.01), while the average age at diagnosis and female dominance remained unchanged during the period. Logistic regression showed that tumour nodules> 1 cm and male gender were the main risk factors for local lymph node metastasis (LNM), whereas patients over 45 years had lower risk. Conclusions During the 22-year period, an increased detection of thyroid cancer, particularly mPTC, was found while the occurrence of LNM decreased. Our results suggest that the current preoperative diagnosis and risk stratification are adequate, supporting the published guidelines for the diagnosis of thyroid cancer.