title: Is the pathological regression level of metastatic lymph nodes associated with oncologic outcomes following preoperative chemoradiotherapy in rectal cancer?
abstract: OBJECTIVE
  The oncologic impact of the lymph node (LN) regression level after preoperative chemoradiotherapy (PCRT) has not been thoroughly evaluated. Hence, this study aimed to examine whether the regression level of metastatic LNs following PCRT is associated with oncologic outcomes in rectal cancer.
  
  
  RESULTS
  The optimal number of cut points for LRG sum was determined to be three. The three LRG groups demonstrated different distributions according to the ypT and ypN stages (p < 0.001 for both). However, the distribution of the LRG groups was not associated with the TRG of the primary tumor (p = 0.527). The RFS significantly differed according to the LRG groups (p = 0.001). Moreover, the differences in RFS remained when the LRG groups were analyzed within each separate ypN stage. The LRG group was confirmed as a factor associated with RFS in the multivariate analysis (p=0.018), while the ypN stage was not (p=0.4).
  
  
  METHODS
  We analyzed the outcomes of 142 rectal cancer patients diagnosed with ypN1 disease after PCRT followed by radical resection. The pathological responses of the primary tumor and LNs to PCRT were evaluated using the tumor regression grade (TRG) and LN regression grade (LRG), respectively. The impact of LRG on recurrence-free survival (RFS) was analyzed. The K-adaptive partitioning for survival data method was applied to determine the optimal number of cut points for the LRG-sum and the optimal number of subgroups.
  
  
  CONCLUSIONS
  The LRG as an indicator of response to PCRT should be considered as a prognostic determinant in rectal cancer patients. Future large-scale prospective studies are needed to confirm this finding.
authors.affiliation: Department of Surgery, Dong Kang Medical Center, Ulsan, Korea.
authors.forename: Jung Pil
authors.initials: JP
authors.lastname: Choi
authors.affiliation: Departments of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Sung Joo
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: In Ja
authors.initials: IJ
authors.lastname: Park
authors.affiliation: Departments of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seung Mo
authors.initials: SM
authors.lastname: Hong
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Jong Lyul
authors.initials: JL
authors.lastname: Lee
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Yoon
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Chan Wook
authors.initials: CW
authors.lastname: Kim
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seok-Byung
authors.initials: SB
authors.lastname: Lim
authors.affiliation: Departments of Clinical Epidemiology and Biostatistics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Jung Bok
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Chang Sik
authors.initials: CS
authors.lastname: Yu
authors.affiliation: Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Jin Cheon
authors.initials: JC
authors.lastname: Kim
mesh_terms: D000368:Aged; D059186:Chemoradiotherapy, Adjuvant / Q000009:adverse effects / Q000401:mortality; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020360:Neoadjuvant Therapy / Q000009:adverse effects / Q000401:mortality; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: lymph node regression; oncologic outcome; preoperative chemoradiotherapy; primary tumor regression; rectal cancer