RELATIONSHIP OF CURATIVE SURGERY ON NATURAL-KILLER-CELL ACTIVITY IN COLORECTAL-CANCER

Aim of this study has been to evaluate natural killer (NK) activity in patients with colorectal tumors before and after curative surgery. ME THODS: Forty colorectal cancer patients without distant metastases wer e stratified according to American Joint Committee on Cancer/Internati onal Union Against Cancer staging system into three categories: Stage I(n = 12), Stage II (n = 15), and Stage III (n = 13). All of them unde rwent curative resection, and there were no major postoperative compli cations. Venous blood samples were obtained preoperatively, at surgica l wound closure, and on the Ist, 7th, and 21st postoperative days. Mon onuclear cells were isolated over Ficoll-Hypaque(TM) (Lymphoprep, Nyco med Pharma AS, Oslo, Norway) gradients, and NK activity was assayed by evaluation of cytotoxic response against K562 cells. Normal NK activi ty was achieved from 15 healthy donors. Percentage relative increments in relation to preoperative levels were calculated for every postoper ative sample, and t-test was used for statistical evaluation. RESULTS: Before surgery, Stages II and III patients had lower levels of NK act ivity than healthy people (P < 0.05 and P < 0.001, respectively). NK a ctivity 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, pati ents did show a significant recovery by the 21st postoperative day(+23 .63 +/- 9.36 and +43.19 +/- 13.34, respectively). At this time, NK act ivity in these two groups was not significantly lower than in normal s ubjects (P > 0.05). CONCLUSION: NK activity is depressed in colorectal cancer patients in relation to progression of illness, even at locore gional stages. Curative resection of tumors at Stages II and III has p romoted a recovery of NK activity in patients with uneventful postoper ative courses.