Although laboratory experiments have suggested that mistletoe extract may affect the immune system and be able to kill some kinds of cancer cells, there is little evidence of its benefit to people with cancer.[5][29] Most of the clinical research claiming that mistletoe therapy is effective is published in Germany, and it is generally considered unreliable because of major lapses in quality.[29][3] Edzard Ernst wrote that research by anthroposophic doctors often reached positive conclusions on mistletoe therapy because it drew on unreliable material; independent researchers tended instead to find no evidence of benefit.[4] The American Cancer Society says that "available evidence from well-designed clinical trials does not support claims that mistletoe can improve length or quality of life".[4]