Boston: An ingredient found in marijuana may help fight lung cancer, the most lethal of all cancers worldwide, say scientists.

In lab and mouse studies, the compound known as THC (Tetrahydrocannabinol) cut lung tumour growth in half and helped prevent the cancer from spreading, said Anju Preet, a Harvard University researcher in Boston who tested the chemical.

Earlier researches suggest that cannabis compound could help fight brain, prostate and skin cancers as well.

The latest finding builds on the recent discovery of the body's own cannabinoid system, Preet said. Known as endocannabinoids, the natural cannabinoids stimulate appetite and control pain and inflammation.

THC seeks out, attaches to and activates two specific endocannabinoids that are present in high amounts on lung cancer cells, Preet said. This revs up their natural anti-inflammatory properties. Inflammation can promote the growth and spread of cancer.

In the new study, the researchers first demonstrated that THC inhibited the growth and spread of cells from two different lung cancer cell lines and from patient lung tumours.

Then they injected THC into mice that had been implanted with human lung cancer cells. After three weeks, tumours shrank by about 50 percent compared with tumours in untreated mice, reported the online edition of health magazine WebMD.

While a lot more work needs to be done, "the results suggest THC has therapeutic potential," Preet was quoted as saying. The findings were presented at the annual meeting of the American Association for Cancer Research. (IANS)