Interleukin 6 signal transducer, IL6ST correlates with survival outcomes in invasive ductal carcinoma

In the United States, breast cancer is the most common cause of mortality among women (1). Breast cancer metastasis, or the spread of cancer from the breast to other organs such as the bones, liver, brain, and lungs, is the leading cause of death in women (2). We combined two separate microarray datasets, one containing transcriptome data from primary breast tumors (3) and the other containing transcriptome data from metastases in women with breast cancer (4), both of which included survival data for the patient from whom each tumor or metastasis sample was obtained. We discovered that the gene encoding the Interleukin 6 signal transducer, IL6ST, gp130 (5), was among the genes whose expression was most variable between patients who lived longer or less than 18 months by comparing tumor transcriptome data depending on survival outcomes. IL6ST was expressed at considerably higher levels in both original breast cancers and metastases in women who survived more than 18 months. These findings support the use of IL6ST as a biomarker or prognostic indicator (6-8) to help determine which women will benefit from more or less intensive treatment regimens based on metastasis prediction; additionally, IL6ST may be fundamentally linked to tumor progression and tumor aggressiveness, implying that IL6ST could be used as a therapeutic target in breast cancer.