Stage III Melanoma: Changes to Staging System

Source: OncLive, August 2019

Jeffrey S. Weber, MD, PhD: The other difficult discussion is the stage IIIa patients. Vern, you obviously see a lot of patients who have stage IIIA disease, and the surgical maxim is that patients who had less than 1 mm of tumor in the sentinel node didn’t go on the adjuvant studies because they did pretty well. And it was the tumor burden volume in the sentinel node that was associated with outcome, so how comfortable do you feel referring a stage IIIA patient for adjuvant therapy with that terrific low risk of relapse?

Vernon K. Sondak, MD: Let’s unpack the question a little bit, because the first thing we need to recognize when we talk about the staging is that the staging system changed and the words we use now mean different things. Stage IIIA, as it was used in all the adjuvant therapy trials that have been reported, in the seventh edition of the American Joint Committee on Cancer (AJCC) staging system meant nonulcerated primary melanoma with 1 or 2 positive sentinel lymph nodes. And among all those nonulcerated melanomas with a positive sentinel node, the patient had to have at least a 1-mm tumor deposit in the sentinel node to get on to the trial.

They also had to have a node dissection, which we don’t do now since MSLT-II. Today stage IIIA switches to only the thinner melanomas—thinner and nonulcerated T1 or T2, with a positive sentinel node. In any size but for the purposes of adjuvant therapy trials, 1 mm was the cutoff. A stage III patient who is stage IIIA in the eighth edition has a better prognosis than we were used to. And most true, eighth edition stage IIIA patients have small tumor deposits. They don’t have larger tumor deposits.