In this study, we have used newly developed Silicon nanowire (SiNW) arrays to evaluate their feasibility for the quantification of different markers of interests. We have quantified four different markers of PSA, EGF, IL-6, and VDBP. Each marker showed measurements in the range of 0.184∼17.79 ng/mL (PSA), 10 pg/mL∼10 ng/mL (EGF), 10 pg/mL∼50 ng/mL (IL-6), and 10 pg∼5 ng/mL (VDBP), respectively. For the experiment, we collected 10 different serum samples, 5 prostate cancer patients and 5 breast cancer patients, and measured and compared the resulting signal from the SiNW FET to serum sample from normal patients. As a result, we observed a meaningful pattern of markers associated with each type of cancer. In addition, we have measured the response signal of SiNWs conjugated with Epithelial cell adhesion molecules (EpCAM) markers against tumor cells as they interacted with those markers.