I cook with olive oil daily. will this cause cancer ?

Everything causes Ca: Frying food releases low grade carcinogens, so use the best ventilation you can. The risk is small but proven epidemiologically (cooks get more Ca) and by sampling air around cooking areas.(http://pubs.rsc.org/en/content/articlelanding/2006/em/b516173h/unauth#!divAbstract) There are much greater cancer risks out there, like smoking and excessive drinking, so I wouldn't get hung up on olive oil.