A new study conducted by scientists at Complutense University in Spain suggests that cannabis extracts may shrink brain tumours and other cancers by blocking the growth of the blood vessels which feed them. According to New Scientist, Manuel Guzman and colleagues have demonstrated how the cannabis extracts block a key chemical needed for tumours to sprout blood vessels.

The team tested the effects of marijuana extract, delta-9-tetrahydrocannabinol in 30 mice and found that it inhibited the expression of several genes related to the production of a chemical called vascular endothelial growth factor (VEGF).

VEGF is critical for angiogenesis, which allows tumours to grow a network of blood vessels to supply their growth. The cannabinoid significantly lowered the activity of VEGF in the mice and two human brain cancer patients, the study showed.

According to teammember, Cristina Blazquez, "We saw that the tumours [in mice] were smaller and a bit pallid. The paleness of the cancer reflected its lack of blood supply as a result of the treatment. In the human patients, she says: "It seems that it works, but it's very early."