Many sarcomas can be tough to treat, other than cutting them out. I had a sick relative that I encouraged to drink tudei and Isa for a couple years as a Hail Mary addition to the chemo. It may have helped, but in the end, it wasn't enough. That is a single anecdote, so definitely not conclusive. Flavokavains seem good at reducing the advance of mutagenesis, but are not a magic bullet once the cancer is advanced. I haven't been keeping up on the kava / cancer literature much since my relative passed away, but I still work in a cancer clinic.