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The first history of melanoma is a risk factor for subsequent diagnoses, regardless of race

The first history of melanoma is a risk factor for subsequent diagnoses, regardless of race

While melanoma is less common in members of racial and ethnic minorities, new evidence suggests that individuals in such groups with a first melanoma diagnosis have a similar rate of a second primary melanoma diagnosis as white individuals.1

These data result from a new analysis authored in part by Shoshana Zhang, BS, of 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 of the risk of second primary melanoma.

Zhang et al. found before the analysis that the risk of later primary melanoma is almost nine-fold increased in melanoma patients compared to others.2

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

Background and design

The research team’s main goal in their research was to track the occurrence of a second primary cutaneous melanoma. The team defined this as any melanoma diagnosis made no later than two months after the first melanoma report. The key variables of interest were race and ethnicity, categorized by the Surveillance, Epidemiology, and End Results (SEER) program.

Researchers examined data from 17 SEER-associated registries to find subjects who had been diagnosed with a first primary cutaneous melanoma between 2000 and 2019. Two hypotheses were proposed to evaluate the risk of developing two primary melanomas.

Specifically, the research team’s null hypothesis assumed that the first and second occurrences of melanoma were independent events, each carrying the same level of risk. In the team’s alternative hypothesis, they worked to estimate conditional risk by examining the likelihood of developing a second melanoma after the initial diagnosis of a first melanoma.

The researchers decided to compare these two models to determine whether the risk of a second melanoma goes beyond what would be expected solely by chance. Excess absolute risks (EARs) and standardized incidence ratios (SIRs) were used by the research team to compare the actual number of second melanomas with the expected number in the general population.

They calculated SIRs by dividing the observed cases by the expected cases. EARs represented the difference between observed and expected cases. All determined rates were adjusted for patient age using the 2000 US standard population.

Key insights

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

Consequently, compared to other racial and ethnic cohorts, under both hypotheses, the researchers found that white subjects had a higher incidence rate of developing two primary melanomas. They added that black subjects had the highest relative risk of developing a second primary melanoma compared to the general population. They had a standardized incidence ratio (SIR) of 264.39.

After the 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 these findings and despite having a lower relative risk, whites were found to have the highest absolute number of excess second primary melanomas.

Specifically, there were 1,332.07 cases per 100,000 person-years. The research team later acknowledged possible limitations to their research.

“Study limitations include the possible misclassification of a recurrent prior melanoma as a second primary melanoma (although there is no reason to believe that this misclassification would occur differently by racial and ethnic group) and the possibility of surveillance bias (ie, diagnostic control), which leads to overestimating the differences between groups,” they wrote.

References

  1. Zhang S, Patel VR, Spencer JC, Haynes AB, Adamson AS. Racial and ethnic disparities in the risk of a second primary melanoma. JAMA Dermatol. Published online October 9, 2024. doi:10.1001/jamadermatol.2024.3450.
  2. Bradford PT, Freedman DM, Goldstein AM, Tucker MA. Increased risk of second primary cancers after melanoma diagnosis. Arch Dermatol. 2010;146(3):265-272. doi:10.1001/archdermatol.2010.2.