In view of the fair safety profile of THC, together with its possible antiproliferative action on tumour cells reported here and in other studies (Guzmán, 2003), it would be desirable that additional trials – on this and other types of tumours – were run to determine whether cannabinoids – as single drugs or in combination with established antitumoral drugs – could be used, other than for their palliative effects, to inhibit tumour growth. In particular, our next goal is to evaluate the efficacy of THC in patients with newly diagnosed gliobastoma multiforme.