ORIGINAL ARTICLE Association between TNM staging system and histopathological features in patients with papillary thyroid carcinoma Hye Jin Baek • Dong Wook Kim • Ji Hwa Ryu Received: 25 April 2014 / Accepted: 7 July 2014 Ó Springer Science+Business Media New York 2014 Abstract We aimed to assess the validity of the American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging system in patients with papillary thyroid carcinoma (PTC) by evaluating the relationships between clinicopathologic factors and TNM stage using histopa- thological specimens and electronic medical records. We enrolled 733 consecutive patients who had undergone thy- roid surgery for PTC between 2010 and 2013. Clinical data were obtained from electronic medical records. TNM stages, multifocality, and bilaterality were analyzed after review of histopathological specimens by applying the AJCC TNM staging system. Multiple statistical analyses were performed to evaluate the correlation between the AJCC TNM staging system and the clinicopathologic factors. Of the 733 patients, there were T stage including T1a (46.9 %, 344/733), T1b (12.6 %, 92/733), T2 (2.0 %, 15/733), T3 (38.1 %, 279/733), T4a (0.4 %, 3/733), and T4b (0 %, 0/733), N stage including N0 (58.9 %, 432/733), N1a (24.3 %, 178/733), and N1b (16.8 %, 123/733), and multiplicity including multifocality (31.1 %, 228/733) and bilaterality (23.7 %, 174/733). There was a significant association between the PTC primary tumor size and T stage, N stage, multifocality, and bilaterality (p \ 0.0001). Multifocality, bilaterality, and the presence of nodal metastasis were most frequently seen in patients with T3 stage (p \ 0.0001). In multivariate logistic regression analyses, T and N stages were indepen- dent predictors of multiple PTCs. The PTC primary tumor size had a significant association with the T and N stages of the AJCC TNM staging system, and these factors were independent predictors of multifocality and bilaterality. Keywords Thyroid Á Papillary carcinoma Á T stage Á N stage Á AJCC Introduction Clinically, the American Joint Committee on Cancer (AJCC)/International Union Against Cancer (UICC) tumor-node-metastasis (TNM) staging system is the most widely used system for classifying differentiated papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma [1–3]. The AJCC TNM staging system was revised in 2010, down-staging T3N0M0 patients with medullary thyroid carcinoma [4]. PTC is the most common type of thyroid cancer and account for 70–90 % of well-differentiated thyroid malig- nancies [5, 6]. Despite 15–30 % local recurrence rate, the majority of PTCs have an indolent clinical course and favorable prognosis [6–8]. Technological advances and a gradual increase in the use of thyroid ultrasound (US) have resulted in continuous increase in the detection of PTC [9–11]. Due to these advances, the prevalence of papillary thyroid microcarcinoma (tumors B1 cm in the largest diameter) has increased; therefore, the majority of PTCs are now diagnosed at a low TNM stage [11]. PTC has a tendency for multiplicity (multifocality or bilaterality), and multiple PTCs are more likely to be aggressive [12, 13]. H. J. Baek Á J. H. Ryu Department of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan 612-896, South Korea e-mail: sartre81@gmail.com J. H. Ryu e-mail: rjhrad@empal.com D. W. Kim (&) Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, 633-165, Gaegeum-dong, Busanjin-gu, Busan 614-734, South Korea e-mail: dwultra@lycos.co.kr; dwultra@naver.com 123 Endocrine DOI 10.1007/s12020-014-0362-3