First Melanoma History is Risk Factor for Subsequent Diagnoses Regardless of Race

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While melanoma is less common among those in racial and ethnic minorities, new findings suggest those in such groups with a first melanoma diagnosis have a rate of second primary melanoma diagnosis similar to that of White individuals.¹

These data resulted from a new analysis which was authored in part by Shoshana Zhang, BS, from Dell Medical School at the University of Texas at Austin. To the best of Zhang’s team’s knowledge, this study was the first to report both absolute and relative measures for secondary primary melanoma risk.

Zhang et al. noted prior to the analysis that those with melanoma have almost a 9-fold risk increase of subsequent primary melanoma compared to others.²

“However, the extent to which risk of a second primary melanoma varies across racial and ethnic groups is less certain,” Zhang and colleagues wrote. “While research has focused on measures of relative risk, less is known about the absolute risk of second primary melanoma across race and ethnicity, which may inform population-level surveillance strategies.”¹

Background and Design

The research team’s main aim of their research was to track the occurrence of a second primary cutaneous melanoma. This was defined by the team as any melanoma diagnosis made subsequently at 2 months minimum following the initial report of melanoma. The key variables of their interest were race and ethnicity, as categorized by the Surveillance, Epidemiology, and End Results (SEER) program.

The investigators looked at data drawn from 17 SEER-associated registries to find subjects who had been given a diagnosis of a first primary cutaneous melanoma in the timeframe between 2000 - 2019. There were 2 hypotheses determined to evaluate risk of 2 primary melanomas being developed.

Specifically, the research team’s null hypothesis assumed that the first and second melanoma occurrences were independent events, with each maintaining the same level of risk. In the team’s alternative hypothesis, they worked to make an estimation of the conditional risk by looking into the likelihood of second melanoma development following the initial diagnosis of a first one.

The investigators decided to compare these 2 models, seeking to determine any excess risk of a second melanoma beyond what would be expected exclusively by chance. Excess absolute risks (EARs) and standardized incidence ratios (SIRs) were used by the research team to compare actual numbers of second melanomas to expected numbers in the general population.

They calculated SIRs through the division of observed cases by expected cases. EARs represented the difference between cases which had been observed versus expected. All of the determined rates were adjusted for patient age through the use of the 2000 standard US population.

Major Findings

Overall, the team concluded that 546,756 subjects had a first primary melanoma diagnosis and, among these, 0.2% had been reported as American Indian or Alaska Native, 0.4% as Black, 3.1% as Hispanic, 0.6% as Asian or Pacific Islander, and 96% as White. They reported that both first primary melanoma (47.67 per 100,000 people) and second primary melanoma (1457.40 per 100,000 person-years) incidence had been the highest among those in the White population.

Consequently, compared to other racial and ethnic cohorts under both hypotheses, the investigators noted that White subjects had a higher incidence rate of developing 2 primary melanomas. They added that compared to those within the general population, Black subjects exhibited the highest relative risk for second primary melanoma development. They had a standardized incidence ratio (SIR) of 264.39.

After Black subjects, there were those in the Asian or Pacific Islander category (SIR: 196.68), those in the Hispanic category (SIR: 62.71), those in the American Indian or Alaska Native category (SIR: 48.47), and those in the White category (SIR: 11.63). Despite such findings, and although they had a lower relative risk, those who were White were noted as having the highest absolute number of excess second primary melanomas.

Specifically, they had 1332.07 cases per 100,000 person-years. The research team later acknowledged any potential limitations to their research.

“Study limitations include potential misclassification of recurring previous melanoma as a second primary melanoma (although there is no reason to believe this misclassification would occur differentially across racial and ethnic groups) and the potential for surveillance bias (ie, diagnostic scrutiny) to overestimate differences across groups,” they wrote.

References

1. ^{Zhang S, Patel VR, Spencer JC, Haynes AB, Adamson AS. Racial and Ethnic Differences in the Risk of Second Primary Melanoma. JAMA Dermatol. Published online October 09, 2024. doi:10.1001/jamadermatol.2024.3450.}
2. ^{Bradford PT, Freedman DM, Goldstein AM, Tucker MA. Increased risk of second primary cancers after a diagnosis of melanoma. Arch Dermatol. 2010;146(3):265-272. doi:10.1001/archdermatol.2010.2.}