title: Relationship of curative surgery on natural killer cell activity in colorectal cancer.
abstract: OBJECTIVE
  Aim of this study has been to evaluate natural killer (NK) activity in patients with colorectal tumors before and after curative surgery.
  
  
  METHODS
  Forty colorectal cancer patients without distant metastases were stratified according to American Joint Committee on Cancer/International Union Against Cancer staging system into three categories: Stage I (n = 12), Stage II (n = 15), and Stage III (n = 13). All of them underwent curative resection, and there were no major postoperative complications. Venous blood samples were obtained preoperatively, at surgical wound closure, and on the 1st, 7th, and 21st postoperative days. Mononuclear cells were isolated over Ficoll-Hypaque (Lymphoprep, Nycomed Pharma AS, Oslo, Norway) gradients, and NK activity was assayed by evaluation of cytotoxic response against K562 cells. Normal NK activity was achieved from 15 healthy donors. Percentage relative increments in relation to preoperative levels were calculated for every postoperative sample, and t-test was used for statistical evaluation.
  
  
  RESULTS
  Before surgery, Stages II and III patients had lower levels of NK activity than healthy people (P < 0.05 and P < 0.001, respectively). NK activity always fell after surgery (Stage I: -18.48 +/- 11.42; Stage II: -16.93 +/- 13.57; Stage III: -35.29 +/- 12.03, at day 1 postsurgery) and appeared to rise slightly by the 21st postoperative day in Stage I patients (+4.87 +/- 12.41). Stage II, and especially Stage III, patients did show a significant recovery by the 21st postoperative day (+23.63 +/- 9.36 and +43.19 +/- 13.34, respectively). At this time, NK activity in these two groups was not significantly lower than in normal subjects (P > 0.05).
  
  
  CONCLUSIONS
  NK activity is depressed in colorectal cancer patients in relation to progression of illness, even at locoregional stages. Curative resection of tumors at Stages II and III has promoted a recovery of NK activity in patients with uneventful postoperative courses.
authors.affiliation: Department of Surgery, Clinic Hospital, University of Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Espí
authors.forename: J
authors.initials: J
authors.lastname: Arenas
authors.forename: E
authors.initials: E
authors.lastname: García-Granero
authors.forename: E
authors.initials: E
authors.lastname: Martí
authors.forename: S
authors.initials: S
authors.lastname: Lledó
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology / Q000601:surgery*; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011184:Postoperative Period