THE PROGNOSTIC-SIGNIFICANCE OF INTRATUMORAL NATURAL-KILLER-CELLS IN PATIENTS WITH COLORECTAL-CARCINOMA

BACKGROUND. Natural killer (NK) cells have a spontaneous cytotoxic cap acity against tumor cells. These cells represent a small proportion of human colon carcinoma-infiltrating lymphocytes. Their prognostic sign ificance in these tumors has yet to be determined. METHODS. One hundre d and fifty-seven patients who each had a colectomy for large bowel ad enocarcinoma were studied. No patient received adjuvant therapy. Immun ohistochemical stains were performed for NK cells using the monoclonal antibody CD57. The number of NK cells was counted using a MICRON imag e analyzer. The total area studied for each tumor was 1 cm(2). In this area, 50 intratumoral fields of 0.173 mm(2) were selected. The degree of NK infiltration was classified as little (< 50 NK cells), moderate (50-150 NK cells), and extensive (> 150 NK cells). The Kaplan-Meier m ethod was used to obtain survival figures. Multivariate analyses were performed using the Cox regression model. RESULTS, At 5 years, patient s with little and moderate NK infiltration showed significantly shorte r survival rates (overall and disease free survival) than those with e xtensive infiltration (P < 0.01). Three significant factors affecting survival were selected in a stepwise fashion in increasing order as fo llows: TNM stage, NK infiltration, and lymphocytic infiltration. Patie nts with TNM Stage III disease and extensive NK infiltration showed si gnificantly longer survival rates than those with little or moderate i nfiltration (P < 0.001). In these patients, multivariate analysis usin g the Cox regression model identified two significant variables: numbe r of involved lymph nodes and NK cell infiltration. CONCLUSIONS, In pa tients with colorectal carcinoma, an extensive intratumoral infiltrati on of NK cells is associated with a favorable tumor outcome. Intratumo ral infiltration of NK cells can be used as a variable with prognostic value, especially in patients with TNM Stage III disease. (C) 1997 Am erican Cancer Society.