A tissue-removing catheter includes a cutting element. A radially innermost portion of the leading radial wall of a raised element of the cutting element may be spaced a radial distance from the longitudinal axis that is less than 66% of the radius of the annular cutting edge. The cutting element may be extendable through the window during operation such that as the cutting element is being rotated about its longitudinal axis, less than an entire radial portion of the leading radial wall passes through the window. A plurality of abrading members may be formed on at least the central portion of the inner surface of the cutting element to abrade hardened tissue as the cutting element is rotating about its longitudinal axis. A radially outermost portion of the leading radial edge of the raised element may be spaced apart radially from an inner surface of the cutting element.