- Detection of circulating tumor cells in peripheral blood of breast cancer patients during or after therapy using a multigene real-time RT-PCR assay. Zehentner, B.K., Secrist, H., Hayes, D.C., Zhang, X., Ostenson, R.C., Loop, S., Goodman, G., Houghton, R.L., Persing, D.H. Molecular diagnosis & therapy. (2006)