My tumors had significant perineural invasion, meaning the tumors were invading the nerve clusters in my breast. One of the statements people make about breast cancer all the time (from doctors to patients and everywhere inbetween) is that "it doesn't hurt unless it's progressed very far," but like most things, there are exceptions to every rule. I had zapping pain intermittently because of that nerve damage until I had my mastectomy, even though I was still just stage 1. I did notice the lumps before that point though, and a lump or other more common signs are usually present with the less common ones. If you are concerned about any change in your body, see a doctor. There's a lot of things besides cancer that can be going on, including harmless stuff. Always best to just see a professional than to spend too much time on google.