Lower postoperative natural killer cell activity is associated with positive surgical margins after radical prostatectomy

Background/Purpose: The inflammatory milieu has been firmly established to affect cancer progression. However, the connection between natural killer (NK) cells and prostate cancer (PCa) has not been elucidated. Methods: Prospective data on NK cell activity (NKA) and NK cell subset distribution patterns were evaluated from 51 patients treated with robot-assisted laparoscopic radical prostatectomy. Whole-blood samples were collected from patients preoperatively and 4–6 weeks postoperatively. The samples were subjected to NKA tests, NK cell number counts, determination of the NKG2D (activating receptor of NK cells), NKG2A (inhibiting receptor), and other surface markers. All the analyses were compared to the clinicopathological characteristics of patients. NKA was estimated by measuring interferon-γ (IFN-γ) levels after stimulation of the peripheral blood with PROMOCA™, which specifically stimulates the release of IFN-γ from NK cells. Results: NKA was lower in patients with PCa than in healthy participants (484.66 vs. 1550 pg/mL). A paired comparison revealed significantly higher NKA postoperatively than preoperatively (1054 vs. 484.66 pg/mL; p = 0.011). Patients with negative surgical margins exhibited significantly higher postoperative NKA and NKA ratio (postoperative NKA/preoperative NKA) than those with positive margins (557 vs. 1921 pg/mL, p