title: Poor survival in stage IIB/C (T4N0) compared to stage IIIA (T1-2 N1, T1N2a) colon cancer persists even after adjusting for adequate lymph nodes retrieved and receipt of adjuvant chemotherapy.
abstract: A survival paradox between Stage IIB/C and Stage IIIA colon cancers exists. It is unclear how adequate lymph nodes dissection (LN) and post-surgery chemotherapy contribute to the survival paradox. We intended to assess the impact of these two factors on the survival paradox.
  
  
  
  We evaluated 34,999 patients diagnosed with stage IIIA or stage IIB/C colon cancer in 2003-2012 from the National Cancer Data Base. The 5-year overall survival (OS) was 73.5 % for stage IIIA and 51.1 % for stage IIB/C (P < 0.0001). The 5-year OS was 84.1 % for stage IIIA with post-surgery chemotherapy, 70.8 % for stage IIB/C with ≥ 12 LNs retrieved with chemotherapy, 53.9 % for stage IIB/C < 12 LNs with chemotherapy, 49.5 % for stage IIIA without chemotherapy, 43.7 % for stage IIB/C ≥ 12 LNs retrieved without chemotherapy, to 27.7 % for stage IIB/C < 12 LNs without chemotherapy. Even among stage IIB/C who had optimal treatment (≥12 LNs retrieved, received chemotherapy), OS remains lower than stage IIIA with chemotherapy. After adjusting LN dissection and chemotherapy in addition to the adjustment of other clinical factors, the survival paradox was reduced from HR = 1.76 (95 % CI: 1.68-1.85) to HR 1.51 (95 % CI: 1.44-1.59).
  
  
  
  LN dissection and post-surgery chemotherapy partially explained the survival paradox. More research is warranted to identify other factors that contribute to this paradox. Future iteration of TNM staging system should take this into consideration.
authors.affiliation: Department of Surgery, Louisiana State University Health Sciences Center, Shreveport, Louisiana, 71130, USA.|Feist-Weiller Cancer Center, Shreveport, Louisiana, 71130, USA.
authors.forename: Quyen D
authors.initials: QD
authors.lastname: Chu
authors.affiliation: Louisiana Tumor Registry and Epidemiology, New Orleans, Louisiana, 71102, USA.|School of Public Health, Louisiana State University Health Sciences Center, New Orleans, Louisiana, 71102, USA.
authors.forename: Meijiao
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Louisiana Tumor Registry and Epidemiology, New Orleans, Louisiana, 71102, USA.|School of Public Health, Louisiana State University Health Sciences Center, New Orleans, Louisiana, 71102, USA.
authors.forename: Kaelen L
authors.initials: KL
authors.lastname: Medeiros
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, 71130, USA. ppeddi@lsuhsc.edu.|Feist-Weiller Cancer Center, Shreveport, Louisiana, 71130, USA. ppeddi@lsuhsc.edu.
authors.forename: Prakash
authors.initials: P
authors.lastname: Peddi
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, 71130, USA.|Feist-Weiller Cancer Center, Shreveport, Louisiana, 71130, USA.
authors.forename: Mindie
authors.initials: M
authors.lastname: Kavanaugh
authors.affiliation: Louisiana Tumor Registry and Epidemiology, New Orleans, Louisiana, 71102, USA.|School of Public Health, Louisiana State University Health Sciences Center, New Orleans, Louisiana, 71102, USA.
authors.forename: Xiao-Cheng
authors.initials: XC
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009367:Neoplasm Staging; D055815:Young Adult
keywords: Colon cancer; Stage IIB/C colon cancer; Stage IIIA colon cancer