First thing is DON'T PANIC, I know easier said than done.
Which breast? Are you left or right handed? What kind of breast cancer?
Has your spouse or a child suffered a traumatic event within the last year?
Conventional medicine does not really understand cancer, the fear of the diagnosis is almost as bad as the disease and the doctors don't help with that one bit.
The medical assumption is that cancer once started is irreversable. This is not true, cancer naturally goes into remission all the time, we may not even know we had cancer.