What are the advantages and disadvantages of different treatments for melanoma?

Several. Melanoma is almost always treated with surgery first; the amount of surgery depends on the clark level (how deep it is), which is measured in millimeter fractions. A sentinel lymph node (first lymph node to respond) is sometimes removed; chemotherapy and targeted molecular therapies are used in certain circumstances.
Surgery is important. Surgical removal of the melanoma sites is usually the most important treatment. Patients with advanced disease that affects multiple other organs may not be surgical candidates. The disadvantage with other treatments like radiation and chemotherapy is that the melanoma is likely to grow back again. Talk with your surgeon & oncologist to find out the best option for you.