THC eradicated brain cancers in some rats, and helped others to live longer, according to a study printed in the March Nature Medicine.
Researchers at Madrid's Complutense and Autonoma Universities injected glioma cancer cells into the brains of 45 rats to produce tumours.

15 rats were left untreated, while 15 had THC infusions for seven days, delivered through a tube to the tumours, and 15 had a synthetic cannabinoid infusion.

The untreated rats all died within 18 days. Tumours disappeared in 3 of the rats which received THC, and 9 of the others lived up to 35 days. 5 of the cannabinoid rats became tumour-free, and 4 more outlived the untreated animals.

Gliomas are highly lethal in humans, and resistant to drugs, surgery and radiation.

Researchers believe that cannabinoids trigger the build-up of a chemical messenger, ceramide, which in turn leads to "programmed cell death" in the tumour. Both THC and the synthetic cannabinoid affected only cancerous brain cells.