Tumour necrosis factor-alpha, interleukin-6, and fasting serum insulin correlate with clinical outcome in metastatic breast cancer patients treated with chemotherapy

INTRODUCTION: To assess the relationship of various growth factors and cytokines with the clinical outcome in metastatic breast cancer patients receiving chemotherapy. METHODS: Consecutive, metastatic breast cancer patients with measurable disease and receiving palliative chemotherapy were prospectively evaluated for the predictors of progression free survival (PFS) and overall survival (OAS) in relation to serum insulin, insulin resistance, interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-alpha). RESULTS: Estrogen receptor (ER) status, serum IL-6 and serum TNF- were the independent determinants of PFS, with RR=0.28 (0.13-0.60), P=0.001, RR=2.48 (1.24-5.61), P=0.012, and RR=0.48 (0.23-1.01), P=0.053, respectively. The factors related with OAS in the multivariate analysis were histological grade (RR=7.88 (2.33-26.62), P=0.001), ER status (RR=0.18 (0.06-0.57), P=0.003), serum insulin (RR=0.87 (0.77-0.97), P=0.016), and serum IL-6 (RR=5.99 (1.89-18.97), P=0.002). CONCLUSIONS: We show for the first time that fasting serum insulin and TNF-alpha levels are independent predictors for OAS and PFS, respectively, in metastatic breast cancer patients. In addition, we also confirm that IL-6 is a poor prognosticator in this group. These results suggest that insulin and TNF-alpha are important biomolecules that may be directly involved in vivo in the progression of metastatic breast cancer.