An ancient native American treatment for cancer has been shown to have a beneficial effect despite scepticism from the medical establishment. Chaparral, an evergreen desert shrub, has long been used by native Americans to treat cancer, colds, wounds, bronchitis, warts, and ringworm. But experts dismissed its worth, and warned it could be dangerous. Now researchers at the Medical University of South Carolina have shown an extract may shrink some tumours. Chaparral tea was widely used in the US as an alternative anti-cancer agent from the late 1950s to the 1970s. However, the American Cancer Society said there was no proof that it was an effective treatment for cancer - or any other disease. And the US Food and Drug Administration warned against its use after research showed it could damage the liver and the kidneys. However, initial results from the latest study show that an extract of the shrub appears not only to be safe, but to have a positive effect. The researchers tested a refined extract taken from chaparral called M4N. They injected it into the tumours of eight patients with advanced head and neck cancer that had not responded to other forms of treatment. The results were encouraging - patients seemed to tolerate it well, and there was no evidence of the serious liver damage previously associated with chaparral use. The study also produced some evidence that the extract had begun to shrink the tumours.