title: Selection of Lymph Node-Positive Cases Based on Perirectal and Lateral Pelvic Lymph Nodes Using Magnetic Resonance Imaging: Study of the Japanese Society for Cancer of the Colon and Rectum.
abstract: OBJECTIVE
  To investigate the optimum cutoff for lymph node size to identify cases positive for perirectal lymph node (PRLN) and lateral lymph node (LPLN) metastasis of lower rectal cancer on magnetic resonance imaging (MRI).
  
  
  METHODS
  The subjects were 449 patients who underwent preoperative MRI. Mesorectal excision was performed in all patients (combined with lateral pelvic lymph node [LN] dissection in 324) between 2004 and 2013 at 6 institutes. Cases were classified as cN positive and cN negative on the basis of the short axis of the largest LN being greater than or equal to a cutoff or less than a cutoff, respectively. PRLN and LPLN diagnoses using 5 and 10 mm cutoffs were compared with histologic diagnoses. Of the 449 patients, 55 received preoperative chemoradiotherapy. MRI was only performed after this therapy in all of these patients.
  
  
  RESULTS
  For PRLNs, 5 and 10 mm cutoffs gave area under the curve (AUC) values of 0.6364 and 0.5794, respectively. The 5 mm cutoff gave a significantly higher AUC value (P = 0.0152), with an accuracy of 63.7 %, sensitivity of 72.6 %, and specificity of 54.7 %. For right LPLNs, the respective AUC values were 0.7418 and 0.6326 (P = 0.0034), and the variables (5 mm cutoff) were 77.6, 68.6, and 79.7 %. For left LPLNs, AUC values were 0.7593 and 0.6559, respectively (P = 0.0057), and the variables (5 mm cutoff) were 79.3, 70.8, and 81.0 %.
  
  
  CONCLUSIONS
  Identification of LN-positive cases on the basis of PRLN and LPLN sizes was superior at a short-axis 5 mm cutoff. Size-based diagnosis of LN metastasis is simple and useful, but further investigation is needed to clarify whether it is superior to diagnosis based on morphology, such as shape, border, and signal intensity.
authors.affiliation: Department of Surgery II, Tokyo Women's Medical University School of Medicine, Tokyo, Japan. ogawa@surg2.twmu.ac.jp.
authors.forename: Shimpei
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Department of Surgery, Kindai University School of Medicine, Osaka-Sayama, Osaka, Japan. hida@surg.med.kindai.ac.jp.
authors.forename: Jin-Ichi
authors.initials: J
authors.lastname: Hida
authors.affiliation: Department of Surgery, Saiseikai Yokohama City Nanbu Hospital, Yokohama, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ike
authors.affiliation: Department of Surgery, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Kinugasa
authors.affiliation: Gastroenterological Center, Yokohama City University Medical Center, Yokohama, Japan.
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Ota
authors.affiliation: Department of Surgery, National Defense Medical College, Tokorozawa, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Shinto
authors.affiliation: Department of Surgery II, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Itabashi
authors.affiliation: Department of Surgery II, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kameoka
authors.affiliation: Department of Surgical Oncology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sugihara
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D010386:Pelvic Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery; D011379:Prognosis; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D012955:Societies, Medical; D055815:Young Adult