Assessment of regression in successive primary melanomas

It has been suggested that patients who have had a melanoma may develop increased immunity against certain antigens expressed by tumor-associated melanocytes. Thus our objective was to review the records of patients with successive primary melanomas to ascertain whether the pattern of regression might indicate the presence of an immunization effect arising from the first melanoma.

A review of all the cases recorded in the melanoma database of our dermatology department between 2000 and 2012 identified 19 patients who had multiple asynchronous melanomas (2.56% of all the cases recorded). We studied the presence or absence of regression in these melanomas and other clinical and histological characteristics.

The presence of regression was significantly higher in successive melanomas than in the first tumors identified (42.10% vs 21.05%, P=.018). Regression of at least 1 melanoma was observed in 42.10% of the patients studied and regression of 2 melanomas was observed in 21.05%. In no case was regression observed in the first melanoma and not in the second; however, in 21.05% of the patients there was evidence of regression in the second tumor and none in the first.

Our findings suggest the possibility that the first melanoma produces an immunization effect in some patients who develop multiple asynchronous melanomas.