Obligate and Potential Precursors of Melanoma
Menée auprès de 3 populations de type caucasien (Australie, Etats-Unis et Ecosse) sur la période 1982-2018, cette étude analyse l'évolution de l'incidence du mélanome in situ et du mélanome invasif
In this issue, Olsen et al. (1) present a test of the hypothesis that melanoma in situ (ie, noninvasive) is an obligate precursor of invasive melanoma. They calculated the incidence rate ratio over time and compared the ages at diagnosis of these 2 conditions. In 3 populations (Queensland, Australia; United States White; and Scotland), the noninvasive to invasive melanoma ratio increased from less than 0.33 in 1980 to 1.95, 0.93, and 0.58, respectively. The mean age at diagnosis of noninvasive was the same or higher than invasive melanoma for most time periods and biopsy sites. These results were considered to be consistent with more indolent lesions coming to clinical attention than in previous eras, challenging the assumption that all or most noninvasive melanomas will ultimately become invasive. As the authors also note (1), the incidence of invasive melanoma has risen steadily over the past 5 decades, whereas mortality has remained largely stable. One explanation for this trend could be that efforts in secondary prevention (screening and surveillance) have shifted the diagnosis toward earlier stages. This could be supported by evidence of an increasing incidence of noninvasive and “thin” (ie, good prognosis) melanomas relative to the potentially lethal “thick” melanomas over this time. However, the absolute incidence of the dangerous thick melanomas has not decreased as a result of these strategies (2).