it's supposed to kill the cancer cells, but sometimes the chemo is so taxing, the body just shuts down.
something similar happened to a friend of mine. Fought lung cancer for 5 years, endured several different kinds of chemo until the medicine stopped working, then his doctors would move to another one.
unfortunately, the last chemo was too hard on his body and his organs just started shutting down. It was less than a week from that new chemo and he just died. surrounded by his loved ones, but dear lord, the very thing that was supposed to cure him actually killed him. He would have lasted longer had he just stopped treatment - he would have had months.