title: Incidence and Risk Factors for Occult Level 3 Lymph Node Metastases in Papillary Thyroid Cancer.
abstract: Papillary thyroid cancer (PTC) frequently disseminates into cervical lymph nodes. Lateral node involvement is described in up to 50 % patients undergoing prophylactic lateral neck dissection. This study aimed to assess this finding and identify which factors predict for occult lateral node disease.
  
  
  
  Patients with fine needle aspiration-confirmed PTC (Bethesda V or VI), without evidence of cervical lymph node metastases, underwent a total thyroidectomy with prophylactic ipsilateral central and level 3 dissection. Level 3 nodes were removed by compartmental dissection or by sampling the sentinel nodes overlying the jugular vein, according to surgeon preference. Data were collected prospectively from January 2011 to August 2014. Statistical analysis was performed by SPSS software.
  
  
  
  A total of 137 patients underwent total thyroidectomy with prophylactic ipsilateral central and level 3 dissection for PTC. The incidence of occult level 3 disease was 30 % (41/137 patients). A total of 48 % of patients (66/137) harbored occult central neck disease. A total of 80.5 % of patients with pN1b disease had macrometastases (≥2 mm), and 15 % exhibited skip metastases with central compartment sparing. In patients with pN1b disease, a median of 6 level 3 nodes were retrieved, with an average involved nodal ratio of 0.29. Multivariate regression demonstrated risk factors for occult lateral neck metastasis include tumor size (odds ratio 1.1), upper pole tumors (odds ratio 6.6), and vascular invasion (odds ratio 3.2) (p < 0.05).
  
  
  
  PTC is associated with a significant incidence of occult central and lateral nodal metastases. In patients undergoing prophylactic central neck dissection, inclusion of level 3 dissection should be considered in patients with large upper lobe cancers.
authors.affiliation: Endocrine Surgery Unit, Royal North Shore Hospital, University of Sydney, St. Leonards, NSW, Australia. sheilafraser@doctors.org.uk.
authors.forename: Sheila
authors.initials: S
authors.lastname: Fraser
authors.affiliation: Endocrine Surgery Unit, Royal North Shore Hospital, University of Sydney, St. Leonards, NSW, Australia.
authors.forename: Nisar
authors.initials: N
authors.lastname: Zaidi
authors.affiliation: Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Olov
authors.initials: O
authors.lastname: Norlén
authors.affiliation: Kolling Institute of Medical Research, University of Sydney, St. Leonards, Australia.
authors.forename: Anthony
authors.initials: A
authors.lastname: Glover
authors.affiliation: Department of Surgical Oncology, University Medical Centre Groningen, Groningen, Netherlands.
authors.forename: Schelto
authors.initials: S
authors.lastname: Kruijff
authors.affiliation: Endocrine Surgery Unit, Royal North Shore Hospital, University of Sydney, St. Leonards, NSW, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Sywak
authors.affiliation: Endocrine Surgery Unit, Royal North Shore Hospital, University of Sydney, St. Leonards, NSW, Australia.
authors.forename: Leigh
authors.initials: L
authors.lastname: Delbridge
authors.affiliation: Endocrine Surgery Unit, Royal North Shore Hospital, University of Sydney, St. Leonards, NSW, Australia.|Kolling Institute of Medical Research, University of Sydney, St. Leonards, Australia.
authors.forename: Stan B
authors.initials: SB
authors.lastname: Sidhu
mesh_terms: D000328:Adult; D001808:Blood Vessels / Q000473:pathology; D002291:Carcinoma, Papillary / Q000556:secondary* / Q000601:surgery*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D065286:Prophylactic Surgical Procedures; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors; D013961:Thyroid Gland / Q000473:pathology; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery*; D013965:Thyroidectomy; D047368:Tumor Burden