I was looking at Mrs T all 45 kilos of her with somewhat puzzled thoughts. I had prescribed her capecitabine at very prudent doses, in view of her 91-year-old kidneys and physiology. She had reduced my treatment even further, because it was making her tired. As a result, she was taking a grand total of 500 mg of capecitabine a day. Yet, her metastatic, ER/PR-negative, Her2-positive breast cancer was undoubtedly responding. Her pain was improving and her chest mass was shrinking, as were her lung metastases What was the secret of that response? Were Mrs T s kidneys eli- nating even less drug...