Cathy, a problem affecting both breasts isn't likely to be breast cancer.  Skin rashes are difficult to diagnose, but they usually aren't breast cancer.  The first thing you could do is to think about whether you've changed laundry detergents or skin care products.  Even if you are using the same one, sometimes people develop an allergy to a product they have used for a long time.  Be sure your bras are well-rinsed.  Try switching to unscented soap for sensitive skin.  But if you don't see a quick improvement, you'll need to see a doctor to find out what this rash is and get the proper treatment.  Although this is almost certainly not cancer or any other dangerous condition, it is uncomfortable and needs treatment so that it doesn't get worse.