Background: Natural Killer (NK) cells are lymphocytes that have a spontaneous cytotoxic activity to recognize and eliminate malignantly transformed cells through early defense against tumors. We aimed to investigate the association between NK cell activity and tumor characteristics, especially in TNM stage, in patients with breast cancer.
Methods: This was a single-center retrospective study. Newly diagnosed breast cancer patients from July 2015 to December 2019 were analyzed. Cytotoxic activity of NK cells was determined using the NK Vue-Kit® (ATgen, Sungnam, Korea) which estimated the level of Interferon-Gamma (IFN-γ) released from NK cells. We transformed IFN-γ levels into natural logs (lnIFN-γ) and analyzed them.
Results: The mean age at diagnosis was 56.3 ± 12.5 years. According to the TNM stage, the median level and range of lnIFN-γ in stage 0, 1, 2, 3, and 4 were 6.91(3.69-7.60) pg/ml, 6.76(3.69-7.60) pg/ml, 6.47(3.69-7.60) pg/ ml, 6.31(3.69-7.60) pg/ml, and 4.23(3.69-6.07) pg/ml, respectively and the P-value was 0.0013. Patients with LN metastases had a significantly lower level of lnIFN-γ than those without LN metastasis (5.78 (3.69-7.60) vs. 6.71 (3.69-7.60) pg/ml, P=0.0017). Patients with distant metastases had also a significantly lower level of lnIFN-γ than those without distant metastasis (4.23, 3.69-6.07 vs. 6.64, 3.69-7.60 pg/ml, P<0.0001).
Conclusion: Progressed breast cancer stage leads to a lower level of lnIFN-γ. It is assumed that IFN-γ released from NK cells decreases as cancer progresses. We suggest that the measurement of IFN-γ levels released from NK cells can be a useful method of surveillance for breast cancer patients.Author(s): Eunhae Um, Jae Il Kim