Need advice from parents of children with cancer

A friend of mine's daughter was diagnosed with stage 3b melanoma, she is 12. She has had surgery to remove the cancer and all the lymphnodes is her affected leg.

My friend is very (over) protective of her daughter and has always done everything to sheild her daughter from any discomfort. My friend is dragging her feet on getting her daughter treatment. She is afraid of the side effects of traditional treatment and is looking into experimental options, which so far have NOT shown to be effective.

Can anyone tell me what can be said to this woman to get her to start treatment? She has even mentioned that her daughter really likes Halloween and wants to put off treatment until after then! She was diagnosed in July. I and her other friends and her husband are at wits end. As it is, she only has a 50% survival rate is she DOES get treatment. If she doesn't, it goes down to 30%, although since she is a child I'm hoping her resilience will improve her odds. I know it must be tough to make these decisions. I'm a breast cancer survivor and did what I had to do to stay alive for my kids, but it's different when the treatment is for a child, especially one who can't tolerate any type of discomfort. Any advice is welcome.

Thanks!