Hi - First of all, try to relax. The chance of you having breast cancer, at age 18, is just about non-existent. Please read our Teen Guide to Breast Development; and our post on fibrocystic change. Both of these pieces will offer you a lot of information about what's normal, and what you should keep an eye on. At your age, there are so many changes going on in your breasts, it's hard to know what exactly is going on... but rest assured, it's almost never breast cancer. Write back if you have any questions after reading those two posts, OK? Good luck - PJH