SFRP2 and breast cancer: The breast cancer patients' median concentration of serum sFRP2 (58 ng/mL) was categorized as a threshold to divide the 274 breast cancer patients into two groups: a high serum sFRP2 group (>58 ng/mL, n = 129) and a low serum sFRP2 group (≤58 ng/mL, n = 145).