Could holding iphone for long periods of time cause hands cancer ?

Conflicting evidence: Although WHO has classified radiofrequency electromagnetic fields as possibly carcinogenic to people. So no one knows but there are ways to minimized and nullify the risk. Namely use a hands free device (ear buds) and in your case, lay the phone on a surface when using away from your body much as poss. Other tips: http://www.cancer.org/cancer/cancercauses/othercarcinogens/athome/cellular-phone