Physicians diagnose the cancer and determine what kind it is by looking at a sample of the tumor under a microscope. This alone does not determine what treatment is needed. Before treatment, doctors must determine if or how much the melanoma has spread. This is called staging the cancer. In melanoma, staging reflects how thick the tumor is and whether or not it has spread to other organs. This is very important because the treatment and the outlook for recovery both depend on the stage of the cancer.
Once identified, a suspected lesion is biopsied. If it is found to be melanoma, it will be surgically removed, often with the surrounding lymph nodes. A number of diagnostic tests may be performed, including a PET/CT scan and a sentinel node biopsy.
Many early melanomas are curable by surgery, and some patients who present with isolated nodal metastases and no distant metastases may be cured by surgical resection of the tumors. However, for disseminated or metastatic melanoma, surgery is not an option and disseminated melanoma is generally poorly responsive to therapy. Therefore, detection of disseminated metastasis is important before deciding on the correct treatment strategy, and a PET/CT scan can play an important role in staging patients suspicious for distant metastasis. In one whole-body picture, the PET scan can look throughout the body to see if there are any cancer cells that have spread. The PET scan can make the difference in determining whether or not surgery should be done.
Detection of disseminated metastatic disease is important to assess the best course of treatment.