The present invention is directed to methods of monitoring cancer stem cells in patients undergoing cancer therapy to determine whether the cancer therapy is an effective cancer therapy. The present invention relates to methods for monitoring the amount of cancer stem cells prior to, during, and/or following cancer treatment of a patient. In particular, the methods provide measuring the amount of cancer stem cells i) in a sample obtained from a patient and/or ii) in a patient via in vivo imaging, e.g. at different time points before, during or after a treatment regimen for cancer. The change in amount of cancer stem cells over time allows the physician to judge the effectiveness of the treatment regimen and then to decide to continue, alter, or halt the treatment regimen if need be. The present invention also provides kits for monitoring cancer stem cells prior to, during, and/or following cancer treatment of a patient. The present invention also provides for a method of treatment of cancer, wherein such method involves the use of a therapeutic agent that stabilizes or reduces the amount of cancer stem cells in or from a patient.
