Natural killer cell activity in prostate cancer patients treated with curative radiotherapy with or without androgen deprivation therapy: an observational study.

background and purposeNatural killer (NK) cells play an important role in defense against cancer. Low NK cell activity (NKA) has been linked to prostate cancer (PCa) detection, and effective NKA may be associated with better prognosis in metastatic PCa. Radiotherapy (RT) could affect the immune response, but data on NKA in patients with PCa receiving RT ± androgen deprivation therapy (ADT) remain limited. Hence, this study investigated NKA in such patients. Patient/material and methods: Peripheral blood from 150 patients with PCa receiving curatively intended RT was collected into NK Vue® tubes prior to RT (baseline, BL), after end of RT (EOT), and during follow-up. Patients received 0- (n = 15), 6- (n = 23), or 36-months of ADT (n = 112), starting 3 months before RT. Interferon-γ was a surrogate marker for NKA in NK Vue® tubes. Data were analyzed using descriptive statistics.

resultsBaseline characteristics were similar between patients with normal (≥ 250 pg/mL) (n = 46) and low (< 250 pg/mL) (n = 104) NKA; however, smoking was more prevalent in the low NKA group (28% vs. 11%). The distribution of NKA levels differed between groups and time points, notably showing a decreased interquartile range (IQR) for all groups at EOT (BL median 832 pg/mL, IQR 2901; EOT median 312 pg/mL, IQR 708). NKA fluctuated during follow-up and did not mirror prostate-specific antigen dynamics.

interpretationPatients with localized PCa treated with RT ± ADT displayed marked variation in NKA, including treatment-related dynamics. The overall complexity and heterogeneity of NKA raise questions about its clinical utility as a biomarker in this setting.