title: Lateral pelvic lymph node dissection can be omitted in lower rectal cancer in which the longest lateral pelvic and perirectal lymph node is less than 5 mm on MRI.
abstract: OBJECTIVE
  The goal of the study was to examine the use of magnetic resonance imaging (MRI) for identification of patients with lower rectal cancer who may benefit from lateral pelvic lymph node dissection (LPLD).
  
  
  METHODS
  Diagnoses and oncological outcomes were examined in 160 cases. Patients in whom the long-axis diameter of the longest detected lymph node was < 5 mm or ≥ 5 mm were classified as LPLN(-) (n = 102) and LPLN(+) (n = 58), respectively.
  
  
  RESULTS
  Diagnostic results gave a 21.6% positive predictive value (PPV) and a 95.0% negative predictive value (NPV) for the LPLN. These values were 59.6% and 91.5%, respectively, for the perirectal lymph node (PRLN). Multivariate analysis showed that a pathologic PRLN (pPRLN)(+) status was an independent prognostic factor for relapse-free survival (RFS) (P = 0.0424) in the LPLN(-) group. The 5-year RFS did not differ significantly between cases that did not and did undergo LPLD (90.0% vs. 83.8%) in the LPLN(-) and pPRLN(-) groups.
  
  
  CONCLUSIONS
  The low PPV and high NPV indicate that it is difficult to identify patients who may benefit from LPLD. However, the results show that LPLD has no benefit in LPLN(-) and PRLN(-) cases and that these cases can be identified based on MRI findings.
authors.affiliation: Department of Surgery II, Tokyo Women's Medical University School of Medicine, Japan.
authors.forename: Shimpei
authors.initials: S
authors.lastname: Ogawa
authors.forename: Michio
authors.initials: M
authors.lastname: Itabashi
authors.forename: Tomoichiro
authors.initials: T
authors.lastname: Hirosawa
authors.forename: Takuzo
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Bamba
authors.forename: Shingo
authors.initials: S
authors.lastname: Kameoka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D010388:Pelvis; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D016896:Treatment Outcome
keywords: lateral pelvic lymph node (LPLN); lateral pelvic lymph node dissection (LPLD); lower rectal cancer; magnetic resonance imaging (MRI)