Just as plants will flourish under certain environmental conditions and perish in others, the biological terrain is what provides an inhibiting environment or an enabling environment for the proliferation of cancer. During chemotherapy my blood counts would hit rock bottom which meant the drugs were killing everything they touched. My oncologist was happy about this, and he was also happy about the fact that my counts would quickly come back up. But he could not explain it. Conventional cancer treatment has no way of knowing if a specific drug will work for a specific person.
Every drug is essentially an experimental drug for any given individual.
In fact, there are research facilities which can test a piece of a person's tumor, and determine which drugs will work best to kill that kind of cancer cell. The conventional approach to cancer treatment is apparently straightforward, and seems to make common sense - detect cancer cells and kill them. The bottom line is that there are no guarantees that simply killing cancer cells will keep you alive - even if you survive the treatment. You have to find ways to keep yourself alive. I believe they have discovered that these are the approaches that will keep them alive.