I notice that you have posted a number of questions about the lump in your breast. It is good to read from one of your previous posts that you have been referred to the hospital to get this checked. Although most lumps turn out not to be cancer it is always sensible to get them checked out. Only seeing the doctor will get you an answer to what this might be. Unfortunately it isn't possible to work this out from how it is responding to the compress you have applied to it. I would also urge you to be cautious about applying heat to your skin as you may accidentally burn yourself.
The best thing to do now is to wait and see what they say at the hospital. It is probably best to avoid checking things out on the internet or lingering here on Cancer Chat as this will keep cancer front of mind to you and wont provide you with any answers as to what it is or give you reassurance.
