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 ER^low and ER^high subgroups, while IL8 retained prognostic significance only in the ER^high 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.