I think he may be speaking of Level 4 (unlikely) or Breslow's 4. Has he had a PET/CT scan?? If there is only local and nodal disease then a cure is possible, but low in the 30 to 40 percent range. If metastatic , and if the local tumor is not problematic he may be able to skip the resection.
There are no really good treatments for Melanoma that had spread via the bloodstream. If localized to local and lymphnodes there may be a possiblility of post op Radiation. I will leave it to Oncryx to discuss systemic therapy.