The clinical usefulness of natural killer cell activity in patients with suspected or diagnosed prostate cancer: an observational cross-sectional study

Purpose: To investigate the clinical usefulness of natural killer cell activity (NKA) for detection of prostate cancer (PCa) and prediction of Gleason grade. Patients and methods: We prospectively enrolled 221 patients who underwent transrectal ultrasound-guided prostate biopsy for suspected PCa due to elevated prostate-specific antigen (PSA) >2.5 ng/mL or abnormal findings on digital rectal examination (n=146), or who were diagnosed with PCa (n=75) between 2016 and 2017. The NKA was compared according to PCa and Gleason grade. Correlation analysis was used to evaluate associations among NKA, PCa, and Gleason grade, and expressed using distribution dot plots. The absolute risk and relative risk of PCa, and odds ratios at different cut-off values of NKA were calculated. Results: Of the total 221 patients, PCa was identified in 135 (61.9%) patients. When patients were divided according to PCa, there was no significant difference in NKA (1,267.6 vs 1,198.9 pg/mL, P=0.491). Furthermore, in 135 patients with PCa, the NKA was not significantly different according to Gleason grade (P=0.893). These results were not changed when confined to the patients with PSA between 2.5 and 10.0 ng/mL (P=0.654 and P=0.672, respectively). In addition, there was no significant difference in the risk of PCa at different cut-off values of NKA. Conclusion: These results indicate that NKA does not appear to be very useful for detection of PCa and prediction of Gleason grade. Further large multi-institutional studies are required to verify the role of NKA in PCa detection and Gleason grade prediction.