First of all, boron, to the best of my scientific knowledge has no role in the treatment of kidney cancer
. So, you should check with your oncologist
as to the reason why he has been put on it. The palpitations that he is having seem to be related to the increased potassium levels that he is having as a result of poor kidney function. It is important to bring down the potassium levels as any further increase can be life threatening. He can take potassium binding resins orally (K-Bind). That should take care of the immediate threat. Meanwhile, avoid taking any drugs that affect the kidney. The treatment of the kidney cancer also needs to be revised. There are a number of other options available like Sorafenib
or Temsirolimus and these need to be discussed with your oncologist before starting.