THC, the main active ingredient in marijuana, cuts lung-cancer tumor growth in half and prevents cancer from spreading, according to a new animal study.

WebMD reported April 18 that researchers from Harvard University injected THC into mice with lung cancer and found that their tumors shrank about 50 percent over three months when compared to mice that didn't receive the drug. The results "suggest THC has therapeutic potential," said lead researcher Anju Preet, Ph.D.

Preet said that THC attaches to endocannabinoids found in cancer cells and activates their natural anti-inflammatory properties, hindering cancer cell growth.

The research was presented at the annual meeting of the American Association for Cancer Research.