title: Prediction of macrometastasis in axillary lymph nodes of patients with invasive breast cancer and the utility of the SUV lymph node/tumor ratio using FDG-PET/CT.
abstract: BACKGROUND
  Axillary lymph node dissection (ALND) is important for improving the prognosis of patients with node-positive breast cancer. However, ALND can be avoided in select micrometastatic cases, preventing complications such as lymphedema or paresthesia of the upper limb. To appropriately omit ALND from treatment, evaluation of the axillary tumor burden is critical. The present study evaluated a method for preoperative quantification of axillary lymph node metastasis using positron emission tomography/computed tomography (PET/CT).
  
  
  METHODS
  The records of breast cancer patients who received radical surgery at the Gifu University Hospital (Gifu, Japan) between 2009 and 2014 were reviewed. The axillary lymph nodes were preoperatively evaluated by PET/CT. Lymph nodes were dissected by sentinel lymph node biopsy (SLNB) or ALND and were histologically diagnosed by experienced pathologists. The maximum standardized uptake value (SUVmax) was measured in both the axillary lymph node (SUV-LN) and primary tumor (SUV-T). The SUV-LN/T ratio (NT ratio) was calculated by dividing the SUV-LN by the SUV-T, and the efficacies of the NT ratio and SUV-LN were compared using receiver operating characteristic (ROC) curve analysis. The diagnostic performance was also compared between the techniques with the McNemar test.
  
  
  RESULTS
  A total of 171 operable invasive breast cancer patients were enrolled, comprising 69 node-positive patients (macrometastasis (Mac): n = 55; micrometastasis (Mic): n = 14) and 102 node-negative patients (Neg). The NT ratio for node-positive patients was significantly higher than in node-negative patients (0.5 vs. 0.316, respectively, P = 0.041). The NT ratio for Mac patients (0.571) was significantly higher than in Mic (0.227) and Neg (0.316) patients (P <0.01 and P = 0.021, respectively). The areas under the curves (AUCs) by ROC analysis for the NT ratio and SUV-LN were 0.647 and 0.811, respectively (P <0.01). In patients with an SUV-T ≥2.5, the modified AUCs for the NT ratio and SUV-LV were 0.757 and 0.797 (not significant).
  
  
  CONCLUSIONS
  The NT ratio and SUV-LN are significantly higher in patients with axillary macrometastasis than in those with micrometastasis or no metastasis. The NT ratio and SUV-LN can help quantify axillary lymph node metastasis and may assist in macrometastasis identification, particularly in patients with an SUV-T ≥2.5.
authors.affiliation: Department of Breast and Molecular Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. mfutamur@gifu-u.ac.jp.
authors.forename: Manabu
authors.initials: M
authors.lastname: Futamura
authors.affiliation: Department of Radiology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. tasa@gifu-u.ac.jp.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Asano
authors.affiliation: Department of Tumor Pathology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. hern@live.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Breast and Molecular Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. kasumimorimitsu@mail.goo.ne.jp.
authors.forename: Kasumi
authors.initials: K
authors.lastname: Morimitsu
authors.affiliation: Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. masax5x5@gmail.com.
authors.forename: Masahito
authors.initials: M
authors.lastname: Nawa
authors.affiliation: Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. m_kanematsu@hotmail.co.jp.
authors.forename: Masako
authors.initials: M
authors.lastname: Kanematsu
authors.affiliation: Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. akemim103@yahoo.co.jp.
authors.forename: Akemi
authors.initials: A
authors.lastname: Morikawa
authors.affiliation: Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. r-mori@wj8.so-net.ne.jp.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Mori
authors.affiliation: Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. k.yoshida@gifu-u.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D001365:Axilla; D001943:Breast Neoplasms / Q000378:metabolism / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D061206:Neoplasm Micrometastasis; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D011379:Prognosis; D012372:ROC Curve; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D021701:Sentinel Lymph Node Biopsy; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18