Son could use a little advice ...

I forgot to mention in my earlier post that it is not mandatory that your mother have herceptin for the full year treatment. There have been clinical trials (FinHer) of herceptin for much shorter periods. The FinHer study was for nine weeks. I believe there is consideration now in New Zealand to use it for nine weeks for early breast cancer. In other words, if you are fearful that a year's treatment will adversely affect your mother's heart, she could do a shorter treatment, avoiding one hopes heart damage.