Equo ne credite, Teucri. Quidquid id est, timeo Danaos et dona ferentes (Do not trust the horse, Trojans! Whatever it is, I fear the Greeks, even bringing gifts) said Laocoön (Virgil, the Aeneid book). Cancer stem cells (CSCs) are populations of cancer cells that can be found in different cancerous tissues and organs, and have properties that are similar to normal stem cells. They are thought to be chemo-resistant and radioresistant and are therefore responsible for cancer recurrence and relapse encountered in cancer patients following chemotherapy and radiotherapy. Although significant progress has been made to characterise CSCs, it is becoming clear that the failure of cancer therapies directed against certain types of aggressive cancers is due to the presence of these malignant cells. Cancer therapies that will rely on a combination of CSCs-targeted therapies, chemotherapy and radiotherapy are more likely to succeed in eradicating aggressive cancers and prevent recurrence in treated patients.