I believe the most effective natural supplement for shrinking a tumor -- after radiation treatments have started to kill it -- is bromelain. Even traditional Western researchers have found that bromelain shrinks some tumors, and a major cancer center (I can't remember which one now, but it was a medical center of the same notoriety as Johns Hopkins) posted on their website many years ago a reference to research on the tumor-shrinking abilities of bromelain. If I remember correctly (it's been years since I researched it), bromelain digests fibrin, of which tumors are partly composed. I took high doses of bromelain both before (for five months) and after (for a couple years) CK. Before treatments, it failed to halt the rapid growth of my AN. But after CK, my tumor rapidly shrank around 70% in volume (after initially swelling due to the radiation). If you want to try this yourself, just be aware that high doses can cause stomach upset and cramping. I found the side effects to be a tolerable trade-off.
Quercitin, resveratrol, curcumin and other natural anti-angiogenesis supplements didn't seem to have any noticeable benefit to me.
My opinions are all based on empirical observations and subjective experience, so take them with a truckload of salt. My tumor shrinkage could have been coincidental or due to some other factor.
My two cents,