The AJCC Staging System 8th Edition: What’s New?
by Mark Faries, MD
Co-Director of the Melanoma Program at The Angeles Clinic and Research Institute
For patients with melanoma, the “Stage” of their tumor is a critically important piece of information. Stage indicates how far a melanoma has progressed. Stage I and II are confined to the skin, Stage III has spread or metastasized through lymphatic channels, generally to lymph nodes, and Stage IV has spread through the bloodstream to distant sites. The staging system enables patients and their physicians to categorize their risk of progression, and, using that prediction, to make informed decisions about what type of treatments to pursue. The last system for melanoma was published in 2009, and the field has changed dramatically over the ensuing years, making those older analyses less applicable to today’s patients.
The American Joint Commission on Cancer (AJCC) develops these staging systems in conjunction with experts in the field, and a new edition (the 8th edition) was recently created. As of the beginning of 2018, it is the official system used in the United States. The Staging Committee used a database that included information from over 43,000 patients treated at major melanoma centers around the world. These patients were all treated using modern techniques, so we know the information is accurate and is applicable to patients today.
One of the most significant changes in the 8th edition is in Stage III melanoma. There is a large spectrum of prognosis for patients with Stage III disease. The new system has increased the number of Stage III categories to four: Stage IIIA, Stage IIIB, Stage IIIC, and Stage IIID. This change enables a much more precise estimate of the long-term outlook for patients and improves on what was possible with the prior edition. For example, patients who fall into the current Stage IIIA category actually have a substantially better outlook than what was true for IIIA’s under the old system. At the other end of the spectrum, Stage IIID is a new category which indicates the highest risk of recurrence and death. These patients are potential candidates for the most intensive follow up and treatment. The improved prediction should also allow for better clinical trial designs to help advance new therapies.
One final twist in staging has occurred due to a change in the standard of care for patients who have melanoma metastases in sentinel lymph nodes. In the past, these patients always would have also had a completion lymph node dissection to follow their sentinel node biopsy, which would allow pathologic evaluation of all of their regional lymph nodes. New clinical trial data has shown that that isn’t necessary for many patients, and many can safely opt for close observation rather than additional surgery. While this is a great option for many patients, it means that those patients won’t have complete staging information since we will no longer know the real extent of their regional involvement. Patients, physicians, and the staging system will have to adapt to this new reality in the coming years.
Mark B. Faries, MD is the Co-Director of the Melanoma Program at The Angeles Clinic and Research Institute, a Cedars-Sinai affiliate in Los Angeles, and the Head of Surgical Oncology there. He is a member of the AJCC Staging Committee for Melanoma and is the Principal Investigator of the Multicenter Selective Lymphadenectomy Trials.