...Ramesh Ganju at the Harvard Cancer Center in Boston, Massachusetts, US, and colleagues deposited human lung cancer cells under the skin of a dozen mice and allowed the tumours to grow in the animals for about two weeks. They then began giving half of these mice daily injections of about 250 micrograms of synthetic THC right next to the tumours for three weeks. A cannabis cigarette may contain as much as 150 milligrams of THC.
Tumours in the control mice averaged about 0.6 grams in weight by the end of the five-week trial. By comparison, those in the mice that received THC weighed just 0.25 grams – 60% less.