title: Significance of size of lymph node metastasis on postsurgical stimulated thyroglobulin levels after prophylactic unilateral central neck dissection in papillary thyroid carcinoma.
abstract: BACKGROUND
  The prognostic significance of size of central lymph node metastasis (CLNM) in papillary thyroid carcinoma (PTC) remains unknown. Because postsurgical detectable stimulated thyroglobulin (DsTg) after radioiodine ablation may imply persistent or recurrent disease, we evaluated the association between size of CLNM and rate of DsTg in patients with PTC who underwent unilateral prophylactic central neck dissection.
  
  
  METHODS
  To be eligible for analysis, the prophylactic central neck dissection specimen with <3 central lymph nodes (CLNs) or size of CLNM ≥1 cm as measured under the microscope was excluded. Of 132 specimens, 89 (67.4%) were eligible. Forty patients (44.9%) had no metastasis or pN0, 20 (22.5%) had micrometastasis (<2 mm) or pN1mic and 29 (32.6%) had macrometastasis (≥2 mm) or pN1mac. Postablation sTg level was measured 9 months after surgery. A multivariable analysis was conducted to identify independent factors for postablation DsTg.
  
  
  RESULTS
  Larger-sized CLNM correlated significantly with younger age (p = 0.028), greater number of CLN retrieved (p = 0.016), greater number of metastatic CLN excised (p < 0.001), higher metastatic CLN ratio (p = 0.006) and postablation sTg level (p = 0.012). In the multivariable analysis, after adjusting for tumor size and metastatic CLN ratio, size of CLNM was an independent predictor of postablation DsTg (odds ratio 1.56, 95% confidence interval 1.09-2.24, p = 0.015). Relative to pN0, the odds ratios for postablation DsTg in pN1mic and pN1mac were 2.53 (95% confidence interval 0.35-19.00, p = 0.351) and 5.81 (95% confidence interval 1.22-27.70, p = 0.027), respectively.
  
  
  CONCLUSIONS
  Size of CLNM was an independent factor for DsTg 9 months after surgery. Patients with pN1mac were almost 6 times more likely to have postablation DsTg than those with pN0 or pN1mic.
authors.affiliation: Division of Endocrine Surgery, Department of Surgery, The University of Hong Kong, Hong Kong SAR, China. blang@hku.hk
authors.forename: Brian Hung-Hin
authors.initials: BH
authors.lastname: Lang
authors.forename: Alex H
authors.initials: AH
authors.lastname: Tang
authors.forename: Kai Pun
authors.initials: KP
authors.lastname: Wong
authors.forename: Tony W
authors.initials: TW
authors.lastname: Shek
authors.forename: Koon Yat
authors.initials: KY
authors.lastname: Wan
authors.forename: Chung-Yau
authors.initials: CY
authors.lastname: Lo
mesh_terms: D055011:Ablation Techniques; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000473:pathology* / Q000556:secondary* / Q000601:surgery; D002291:Carcinoma, Papillary; D002648:Child; D016001:Confidence Intervals; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D053208:Kaplan-Meier Estimate; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009333:Neck; D037981:Neck Dissection; D061206:Neoplasm Micrometastasis / Q000473:pathology; D016017:Odds Ratio; D011184:Postoperative Period; D013954:Thyroglobulin / Q000097:blood*; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000556:secondary* / Q000601:surgery; D013965:Thyroidectomy; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin