 selenium-caus tumour 10 23 heterozyg rat administ 10 seo 1 food 12 protein surviv 18 month cancer liver metastas lung sarcoma adenoma record seri incomplet experi anim fed higher quantiti protein selenium 14-19 month three sarcoma sarcoma lymphat node on- mediastinum suggest chang caus selenium compound extent antagonist relationship methionin 