The present invention provides a novel approach to cancer diagnosis and therapy of cancer by providing compositions and methods for the identification and specific targeting of the cancer stem cell populations present in a tumor to eradicate, or slow or prevent tumor (5) growth and spread, including the potential for tumor metastasis, by modulation of the Renin-Angiotensin System including, but not limited to, Renin Receptor, Angiotensin II Receptor (2) and a secreted form of the Renin Receptor.