Breast cancer and breast tissue cancer is the same thing there is no difference. From 1975 to 2000 1.3 in every one million 15-19 year olds were diagnosed with breast cancer. It is very unlikely your friend has breast cancer if she is only 15 years old.
http://www.goarticles.com/cgi-bin/showa.cgi?C=2368278
Hey ljoan I'm going threw the same thing b4 my period my breast feel painfull but after my period the pain goes away ... How ever one of my breast seem to b notisably bigger I had a kidney transplant and I wonder if every 3 months when I take regular blood test and daily check ups they would b able to detect anything .. I heard it could be hormones or a cyst but I'm honestly not scared if its cancer having a strong mentality can take u far and I recommend u stay calm you are bigger then your fears ! And only we have control of our life and we can't let anything get in the way we need to stay possetive and be real strong I hope everybody lives happy n if anyday at some point in life were sick we r strong enough to figh that sickness!
Dear ljoan: In short, yes, hormones can cause tenderness in one breast more than another. At 46, you may also be perimenopausal which can result in very wide hormone fluctuations. If this mass has been stable size wise for over 2 years and does not feel or image suspiciously, it is unlikely to be cancer. However, you could ask if anyone is willing to biopsy for your own peace of mind.