246 African American patients with melanoma present with lesions of greater Breslow thickness, Clark level, and mitotic rate compared to non-Hispanic white patients with melanoma when controlled for histologic subtype

Abstract

Prior studies examining racial disparities in melanoma presentation have found that African-American (AA) patients generally present at a later stage at diagnosis, have a worse overall survival, greater Breslow depth, and greater Clark level compared to white patients. However, prior studies have not controlled for histologic subtype, namely that acral lentiginous melanomas (ALM) are the most frequent subtype observed in AA patients and superficial spreading melanoma (SSM) the most common subtype in Caucasian patients. Previous reports have shown that ALM confers a worse prognosis and greater Breslow depth at diagnosis than SSM. To address this shortcoming, we performed a retrospective case-control study of melanoma patients seen at the University of Pennsylvania Health System from 1986 to 2016. We compared the paired differences of three histologic prognostic factors, Breslow depth, Clark level, and mitotic rate, for each AA case patient (n¼52) with four matched non-Hispanic white (N-HW) control patients diagnosed with the same histologic subtype of melanoma. Because of concerns that differences in the characteristics of interest may be reflections of differences in physicians' diagnostic ability over time, matched N-HW cases had to be diagnosed within a ten-year period of the date of diagnosis of the AA patient. We found that AA patients had a significantly greater Breslow depth (mean 2.7 vs 0.76, p < 0.0001), higher mitotic rate (mean 4.4 vs 0.64, p < 0.0001), and had a significantly different distribution of Clark level (p < 0.001) compared with matched N-HW controls. These results show that differences in several important tumor characteristics exist between African American and non-Hispanic white patients, highlighting an important racial disparity that may have significant public health implications for the African American population.