title: A minimum yield of twelve lymph nodes in rectal cancer remains valid in the era of neo-adjuvant treatment : results from a national cohort study.
abstract: OBJECTIVE
  The purpose of the study was to examine if a minimum of 12 lymph nodes (LNs) is still valid in rectal cancer after neo-adjuvant treatment.
  
  
  METHODS
  An analysis was carried out in a nationwide Danish cohort of 6793 patients, treated by curative resection of stage I-III rectal cancer during the period 2003-2011. The cohort was divided into two groups according to whether neo-adjuvant treatment had been given. The groups were analysed separately and were further analysed according to four lymph node yield (LNY) groups 0-5, 6-11, 12-17 and ≥18.
  
  
  RESULTS
  Two thousand one hundred twenty-three patients (31.0 %) received neo-adjuvant treatment. A median LNY of 10 and 15 (p < 0.0001) and rates of node-positive (N-positive) disease of 31.6 and 36.7 % (p < 0.001) were observed with and without (+/-) neo-adjuvant treatment, respectively. The rate of N-positive disease according to tumour stage ranged from 4.8 %/11.4 % (ypT0/pT1) to 42.1 %/64.1 % (ypT4/pT4). The rate of N-positive disease according to LNY ranged from 19.5 %/16.8 % (0-5 LNs) to 42.6 %/37.9 % (≥18 LNs) (-/+neo-adjuvant treatment). In a logistic regression analysis, a significant association was found between N-positive disease and pT/ypT stage as well as between N-positive disease and LNY.
  
  
  CONCLUSIONS
  A significantly smaller ratio of N-positive disease was observed in the group of patients who had received neo-adjuvant treatment. The ratio of N-positive disease increased significantly with more advanced tumour stage and increasing LNY irrespective of neo-adjuvant treatment. A minimum of 12 LNs is needed to ensure N-negative disease, irrespective of neo-adjuvant treatment.
authors: Department of Surgery, Herlev Hospital, University of Copenhagen, Herlev, Denmark, jaklyk@gmail.com.
authors: Jakob
authors: J
authors: Lykke
authors: Per
authors: P
authors: Jess
authors: Ole
authors: O
authors: Roikjaer
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D016015:Logistic Models; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D012004:Rectal Neoplasms / Q000473:pathology* / Q000601:surgery / Q000628:therapy*; D012189:Retrospective Studies
references: J Clin Pathol. 2004 Mar;57(3):335-6
references: 14990616
references: Am J Surg. 2012 Dec;204(6):843-7; discussion 847-8
references: 22981183
references: J Clin Oncol. 1999 Sep;17(9):2896-900
references: 10561368
references: Ann Surg Oncol. 2005 Feb;12(2):111-6
references: 15827790
references: J Gastroenterol Hepatol. 1991 Jul-Aug;6(4):325-44
references: 1912440
references: N Engl J Med. 2001 Aug 30;345(9):638-46
references: 11547717
references: Ann Surg. 2001 Nov;234(5):633-40
references: 11685026
references: JAMA. 1975 Mar 3;231(9):969-71
references: 1173109
references: Colorectal Dis. 2009 Mar;11(3):254-8
references: 18513188
references: J Clin Oncol. 2011 Dec 1;29(34):4568-73
references: 21990400
references: Br J Surg. 1986 Jan;73(1):58-60
references: 3512023
references: World J Gastrointest Surg. 2012 Jan 27;4(1):9-19
references: 22347537
references: World J Surg. 2002 Mar;26(3):384-9
references: 11865379
references: Dis Colon Rectum. 2012 Sep;55(9):1002-7
references: 22874609
references: Colorectal Dis. 2013 Apr;15(4):394-403
references: 22958550
references: J Clin Oncol. 2004 Aug 15;22(16):3408-19
references: 15199089
references: Cochrane Database Syst Rev. 2012 Mar 14;(3):CD004078
references: 22419291
references: Ann Surg Oncol. 2010 Jun;17(6):1471-4
references: 20180029
references: Br J Surg. 1989 Nov;76(11):1165-7
references: 2688803
references: J Clin Oncol. 1999 Aug;17(8):2396
references: 10561302
references: J Natl Cancer Inst. 2001 Apr 18;93(8):583-96
references: 11309435
references: J Gastrointest Surg. 2009 Feb;13(2):269-74
references: 18850250
references: Colorectal Dis. 2014 Apr;16(4):O144-9
references: 24329928
references: J Clin Pathol. 2011 Dec;64(12):1073-7
references: 21821862
references: Ann Surg. 2010 Aug;252(2):336-40
references: 20647928