Just to avoid confusion with the use of the word 'extract.'
I told my doctor it was helping me, and she prescribed Marinol. All it did was make me high but did nothing for the nausea and vomiting. Marinol is not plant extract -- it is synthetic -- and although it may be chemically similar to the active ingredient in weed, it does not do the same job.
There is something in the smoke that is not in the Marinol. And that "something" saved my life by allowing me to drink fluids and eat a little during that horrible few months.
(The chemo/rad treatment worked, btw, and I am cancer free since October.)
If anyone has a loved one suffering through chemo, forget Marinol and get your hands on some weed and a pipe.