Look up the Warburg effect. This suggests that many cancers run on sugars. This suggests a possible three (3) approaches below:
1. A strict ketogenic diet (very low carbs)
2. The very cheap drug Metformin. This is the same as the diabetes drug Glucophage. There have even been some cancer drugs in development that mimic what this does at far higher cost.
3. The proton pump inhibitor Nexium. This is also quite cheap and no prescription is even needed.
The concept is to prevent the cancer cells from controlling their local PH while also limiting their sugar supply. You would need to also monitor blood sugar to stay in a safe range.
The good news: this is cheap, easily obtained, and probably pretty safe. There is also at least a plausible mechanism them to work, unlike most naturopathic stuff.
The bad news: requires research into current clinical trials for these three things to determine whether they are useful, or have ever been combined together.
Please note: I am not a medical doctor and can only offer scientific concepts, NOT medical advice. At this point, this is mostly a scientific proposal. If you have any intent to try any of the above, it is imperative that you work through an actual doctor, and obtain their advice.