Im not sure about cancer but it can be abig breeder of nacteria. It is not recomended that you use powder in moist areas-ie. the bottom or underarms as when it is moist it breeds bacteria which can cause not only nappy rash but infection. its fine for use on tummy and arms and legs but steer clear from using on babies bottoms!!
hope this helps a little!
Kathryn - Zack-4, Toby-2 & Molly 1