My sister had stage 4 small-cell lung cancer. She had already become very weakened from it because they were treating her for heart failure instead of finding it (she did not have heart failure, just symptoms of it). They told her that she was too far gone to be treated when they found it. She told them she wanted treatment anyway. They argued, and she stood firm.

She went through chemo and radiation, and it was not pretty, but when it was over, they told her the cancer had shrunk some. She kept getting PET scans every 3 months, and the first two, she just found that it had not grown, but had not shrunk anymore. Then suddenly they came in perplexed. The cancer was gone. Poof! They couldn't explain. She was cancer-free for over 7 years and passed away from something else. So there is hope.