Believe me, a slow, arduous, neurological death is not preferable to a cancerous one. Mindful, these were well within the tolerable limits of up to 55gy but radiated to the whole brain. The optimal dose of radiation necessary to destroy microscopic foci of tumor after surgical resection of a single brain metastasis is unknown. It results from direct injury to brain tissue and blood vessels. The risk increases with higher total dose, higher dose per fraction and with concomitant use of neurotoxic chemotherapeutic agents.
Chemotherapy affects both normal and tumor cells.
The effect on normal cells is the cause of side effects from chemotherapy. The group of drugs called nitrosoureas like Cisplatin, Cisplatinum or Carboplatin are such drugs and natural substances such as Taxol, also cross the barrier. My wife had previous chemotherapy treatments of Taxol and Carboplatin. The body's immune system attacks and eliminates not only bacteria and other foreign substances but also cancer cells. Cancer cells are not foreign to the body but their biological function has been altered in that it doesn't respond to the body's normal mechanisms for controlling cell growth and reproduction.