I like echinacea a lot and our friend Unyquity makes a wonderful echinacea tincture. Essiac tea is a mildly successful cancer fighter in it's own regard, but is a wonderful cleanser for the kidneys and rest of the body.
I also recommend that you read the "Oleander Series" at:
It may be that you can either obtain a supplement form of oleander or else find some oleander to make your own extract with (of course you must use caution and follow directions closely if you make your own, since oleander is quite toxic in raw form). Oleander is not only highly, highly effective against cancer, it also potentiates chemo treatment and either eliminates or greatly lessens all known side effects of chemo.
The amounts given should be adjusted for the body weight of the child - figuring that the listed doses are appropriate for a 150 to 180 pound adult.