Interleukin-6 and interleukin-8 serum levels in prognosis of hormone-dependent breast cancer

Background: Increasing amount of evidence points to the importance of immunity in breast cancer. The prognostic value of cytokines and their effect on tumorigenesis remains inconsistent. Aim: To investigate the prognostic significance of IL6 and IL8 and their association with ER and HER2 in estrogen -dependent (ER +) breast cancer. Material and methods: The study included 79 premenopausal women with early and locally advanced ER + breast cancer. All patients received adjuvant hormonal therapy: tamoxifen alone (56/79) or combination with LHRH agonist goserelin (23/79). IL6 and IL8 serum protein levels were measured by ELISA. Cox proportional hazards regression analysis was implemented for prognostic evaluation of the data categorized based on metastasis outcome. Results: IL6 associated with good (P = 0.001, HR = 0.05) and IL8 with poor disease outcome (P = 0.03, HR = 2.5) in the whole group of patients. Multivariate analyses highlighted IL6 as the independent prognostic factor (P = 0.001, HR = 0.0007). When patients were classified according to ER or HER2 status, IL6 did not have prognostic significance in ERlow and ERhigh subgroups, while IL8 retained prognostic significance only in the ERhigh subgroup (P = 0.04, HR = 2.8). IL6 was significant in both HER2 (P = 0.001, HR = 0.05) and HER2+ subgroups (P = 0.002, HR = 0.04), while IL8 retained its prognostic significance only in the HER2+ subgroup (P = 0.001, HR = 77.8). Conclusions: This study contributes to the clarification of the prognostic performance of IL6 and IL8 by providing their first prognostic evaluation in the homogenized ER + breast cancer patient group. IL6 was indicated as a marker of favorable, whereas IL8 was a marker of unfavorable disease outcome.