title: (18)F-FDG PET/CT-positive internal mammary lymph nodes: pathologic correlation by ultrasound-guided fine-needle aspiration and assessment of associated risk factors.
abstract: OBJECTIVE
  Metastatic breast cancer in internal mammary (IM) lymph nodes is associated with a poor prognosis. This study correlates (18)F-FDG PET/CT-positive IM lymph nodes with ultrasound-guided fine-needle aspiration (FNA) cytopathologic results and determines risk factors for IM node positivity on PET/CT.
  
  
  METHODS
  For this retrospective study, a database search was performed to identify patients referred for whole-body (18)F-FDG PET/CT for initial staging or restaging of breast cancer from January 1, 2005, through December 31, 2010. The radiology reports and images were reviewed for patients with (18)F-FDG-avid IM lymph nodes on PET/ CT and correlated with the cytopathologic results from FNA of selected PET/CT-positive IM lymph nodes. The patients with positive IM nodes on PET/CT who underwent PET/CT for initial staging were compared against age-matched and tumor size-matched patients to identify risk factors for IM node positivity on PET/CT.
  
  
  RESULTS
  One hundred ten of 1259 patients (9%) had an (18)F-FDG-avid IM lymph node on PET/CT. Twenty-five patients underwent ultrasound-guided FNA of a suspicious IM node, and 20 IM lymph nodes (80%) were cytologically proven metastases from the primary breast malignancy. High tumor grade, the presence of lymphovascular invasion (LVI), and triple receptor-negative hormonal receptor status were found to be significant risk factors for IM node positivity on PET/CT (p < 0.05).
  
  
  CONCLUSIONS
  Although fewer than 10% of breast cancer patients have positive IM nodes on (18)F-FDG PET/CT performed for initial staging or restaging, a positive IM node indicates a very high likelihood of malignant involvement on ultrasound-guided FNA. The presences of high tumor grade, LVI, or triple receptor-negative status are risk factors for IM node positivity on (18)F-FDG PET/CT.
authors.affiliation: Swedish Cancer Institute, Seattle, WA 98104, USA. wangcl@uw.edu
authors.forename: Carolyn L
authors.initials: CL
authors.lastname: Wang
authors.forename: Marna J
authors.initials: MJ
authors.lastname: Eissa
authors.forename: James V
authors.initials: JV
authors.lastname: Rogers
authors.forename: Aleksandr Y
authors.initials: AY
authors.lastname: Aravkin
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Porter
authors.forename: J David
authors.initials: JD
authors.lastname: Beatty
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D061765:Endoscopic Ultrasound-Guided Fine Needle Aspiration / Q000706:statistics & numerical data*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged; D064847:Multimodal Imaging / Q000706:statistics & numerical data*; D049268:Positron-Emission Tomography; D015995:Prevalence; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D014057:Tomography, X-Ray Computed; D014861:Washington / Q000453:epidemiology
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18