title: Thyroid nodule size and prediction of cancer.
abstract: BACKGROUND
  Thyroid nodule size is routinely measured, although its impact on thyroid cancer risk is unclear.
  
  
  OBJECTIVE
  Our objective was to evaluate the association of nodule size upon cancer risk.
  
  
  METHODS
  We conducted a retrospective cohort analysis at an academic hospital with 4955 consecutive patients evaluated between 1995 and 2009.
  
  
  METHODS
  Ultrasound and ultrasound-guided fine-needle aspiration of nodules >1 cm was done. Indeterminate and malignant nodules were referred for surgery, and histopathology was reviewed.
  
  
  METHODS
  The presence and histological subtype of cancer was evaluated.
  
  
  RESULTS
  Of 7348 evaluated nodules, 927 (13%) were cancerous. Of those 1.0 to 1.9 cm in diameter, 10.5% were cancerous. In contrast, of those >2.0 cm, 15% were cancerous (P < .01). However, nodules 2.0 to 2.9, 3.0 to 3.9, and >4 cm were cancerous in 14%, 16%, and 15% of cases (P = .14), respectively, demonstrating no graded increase in risk beyond the 2-cm threshold. When malignant, the proportion of papillary carcinoma decreased (nodules 1.0-1.9 cm, 92% of cases; 2.0-2.9 cm, 88%; 3.0-3.9 cm, 83%; >4 cm, 74% [P < .01]), while follicular carcinoma increased (1.0-1.9 cm, 6%; 2.0-2.9 cm, 7%; 3.0-3.9 cm, 12%; >4 cm, 16% [P < .01]) as nodules enlarged. Nodules size did not influence cytology distribution or risk of false-negative aspirates.
  
  
  CONCLUSIONS
  Increasing thyroid nodule size impacts cancer risk in a nonlinear fashion. A threshold is detected at 2.0 cm, beyond which cancer risk is unchanged. However, the risk of follicular carcinomas and other rare thyroid malignancies increases as nodules enlarge.
authors.affiliation: Thyroid Section, Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, 75 Francis Street, PBB-B4, Room 417, Boston, Massachusetts 02115, USA.
authors.forename: Sophia C
authors.initials: SC
authors.lastname: Kamran
authors.forename: Ellen
authors.initials: E
authors.lastname: Marqusee
authors.forename: Mathew I
authors.initials: MI
authors.lastname: Kim
authors.forename: Mary C
authors.initials: MC
authors.lastname: Frates
authors.forename: Julie
authors.initials: J
authors.lastname: Ritner
authors.forename: Hope
authors.initials: H
authors.lastname: Peters
authors.forename: Carol B
authors.initials: CB
authors.lastname: Benson
authors.forename: Peter M
authors.initials: PM
authors.lastname: Doubilet
authors.forename: Edmund S
authors.initials: ES
authors.lastname: Cibas
authors.forename: Justine
authors.initials: J
authors.lastname: Barletta
authors.forename: Nancy
authors.initials: N
authors.lastname: Cho
authors.forename: Atul
authors.initials: A
authors.lastname: Gawande
authors.forename: Daniel
authors.initials: D
authors.lastname: Ruan
authors.forename: Francis D
authors.initials: FD
authors.lastname: Moore
authors.forename: Karla
authors.initials: K
authors.lastname: Pou
authors.forename: P Reed
authors.initials: PR
authors.lastname: Larsen
authors.forename: Erik K
authors.initials: EK
authors.lastname: Alexander
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012306:Risk; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D016606:Thyroid Nodule / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D014463:Ultrasonography