Are sunscreens safe/ which brands?

Well im kind of bummed because I use sunscreen everyday because I am on a medicine that makes me HAVE to wear sunscreen when I go outside. Anyways, I heard sunscreen can cause cancer? Is this true? I know which ingrediants cause it because I just looked and im a little freaked out. Anyways im going on a cruise next week and I will be wearing a lot of sunscrren. If sunscreen is not safe which brands or what kind of sunscreen can I buy so I dont have to worry about wearing it? Thanks.