title: Defining a New Tumor Dimension in Staging of Papillary Thyroid Carcinoma.
abstract: BACKGROUND
  Cervical lymph node metastasis is a vital factor associated with local recurrence in papillary thyroid carcinoma (PTC). Tumor size is used in the staging of PTC because it represents the tumor load. This study compared two methods of tumor size assessment to predict tumor behavior in the relationship between size and cervical node involvement for patients with PTC.
  
  
  METHODS
  The study enrolled 1084 patients who underwent initial thyroid surgery and had a pathologic diagnosis of PTC between 2012 and 2014 at The Second Affiliated Hospital Zhejiang University School of Medicine. Cervical lymph node metastasis (LNM) risk was analyzed according to the clinicopathologic features. For each patient with multifocal disease, two tumor size estimates were used: (1) the dominant focus size and (2) the aggregate size, calculated as the sum of the maximal diameters of all tumor foci.
  
  
  RESULTS
  Of the 1084 patients, 294 (27.1%) had multifocal cancer lesions, and 49% of these patients had cervical LNM, compared with 38.1% who had unifocal disease (P = 0.001). The use of aggregate dimension significantly increased the tumor size and reclassified significant numbers of multifocal PTCs to a more advanced T stage. This aggregate dimension took account of all tumor foci and predicted LNM risk at a proportion identical with that for size-matched, unifocal tumors.
  
  
  CONCLUSIONS
  Multifocality together with aggregate tumor size is a more accurate predictor of node status and, by inference, tumor behavior in the relationship between tumor size and cervical node involvement.
authors.affiliation: Department of Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Clinical Medicine, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Chundi
authors.initials: C
authors.lastname: Miao
authors.affiliation: Department of Clinical Medicine, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Haichao
authors.initials: H
authors.lastname: Yan
authors.affiliation: Department of Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Qiuping
authors.initials: Q
authors.lastname: Xie
authors.affiliation: Department of Clinical Medicine, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Jaiswal
authors.initials: J
authors.lastname: Sanjay
authors.affiliation: Department of Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China. zqz0167@gmail.com.
authors.forename: Qunzi
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000556:secondary* / Q000601:surgery; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D055815:Young Adult