I had a lump in my breast for years and wasn't until I noticed it getting slightly bigger about two years ago that I went to my GP about it. She examined my breasts and refferred me to a specialist at my local hospital, they sent me for an ultrasound and found out I actually had two - they weren't cancerous and they don't normally take them out on women under 25 because the chances of them turning cancerous are so small, but because they were so big and took up a lot of space in my breast, they recommended I have them taken out.
Few weeks later I had a small operation to remove both of them, only took about an hour and I was home by lunchtime, no problems at all. They sent the tissues off to be examined and it turns out they were both fibroadenoma, lumps that many young women get during puberty and not dangerous at all.