Itching, or pruritis as it is medically known, is a fairly common condition. There are many causes of pruritis, some of which a minor and some of which can be significant. I would recommend you discuss this with your primary care doctor
. If necessary, your doctor may refer you to a dermatologist
-- or skin specialist -- who can better help you.
Firstly, this would be a very, very unusual presentation fo breast cancer. Breast cancer is relatively rare in women your age, and most often presents as a painless lump. Itching is not a common symptom of this cancer. Talk to your doctor for more information.
So what could be causing itching? As your rightly point out, the fact that it is limited to your breast area means that it might be caused by something you are putting on your breasts. The bra or lotion may be causing a skin reaction. This normally would be associated with visible skin changes. Rarely, underlying conditions can cause this. For example, breast engorgement during pregnancy can sometimes cause itching. People with severe thyroid problems or liver problems can also feel itchy -- but this would often be associated with other symptoms.
See your doctor for more information. This should be evaluated, it is unlikely breast cancer but there could be another cause. Good luck!