I assume you are... Asking on behalf of a child known to you. For a long time now, the mainstay of therapy has been surgical resection and chemotherapy that includes 5fu, (fluorouracil) Cisplatin and vincristine. For some patients with extensive disease, a liver transplant may be required because an adequate surgical resection can't be achieved. There are ongoing clinical trials geared toward further improvements in outcomes.
Surgery and chemo. The treatment depends on the certain characteristics of the disease. These are known from the initial biopsy. From there the treatment typically involves chemo followed by a second tumor resection.