Molecular screening of interleukin-6 gene promoter and influence of -174G/C polymorphism on breast cancer.

Interleukin-6 (IL-6) is a cytokine involved in different physiologic and pathophysiologic processes including carcinogenesis. In 2003, a single nucleotide polymorphism (-174G/C) of the IL-6 gene promoter has been linked to breast cancer prognosis in node-positive (N+) breast cancer patients. Since, different studies have led to conflicting conclusions about its role as a prognostic and/or diagnostic marker. The primary aim of our study was to investigate the link between -174G/C polymorphism and breast cancer risk on the one hand, and -174G/C polymorphism and prognosis in different groups of patients: sporadic N+breast cancers (n=138), sporadic N- breast cancers (n=95) and familial breast cancer (n=60) on the other hand. The variables of interest were disease-free survival and overall survival. The secondary aim of the study was to screen IL-6 gene promoter using direct sequencing to identify new polymorphisms in our French Caucasian breast cancer population. No association or trend of association between -174G/C polymorphism of IL-6 gene promoter gene and breast cancer diagnosis or prognosis was shown, even in meta-analyses. Furthermore, we have identified four novel polymorphic sites in the IL-6 gene promoter region: -764G-->A, -757C-->T, -233T-->A, 15C-->A.