Memorial Sloan-Kettering medical oncologist Paul Chapman says that pigmented cells called melanocytes, which normally remain in the skin, can travel throughout the body when certain genes become mutated. Once melanoma begins to spread, it can be much more difficult to treat with standard chemotherapy and radiation.
Surgical oncologist Charlotte Ariyan explains that the risk of developing metastatic disease depends on the thickness of the melanoma. The vast majority of small, localized melanomas can be removed with surgery. More extensive surgery may be required to treat larger, thicker melanomas. Sentinel lymph node biopsy – injecting a radioactive dye near the tumor to identify the lymph node into which it drains – is used to determine if cancer cells have spread. If the sentinel lymph node contains cancer cells, additional lymph nodes may be removed to prevent the melanoma from spreading further.