Risk of a Second Primary Melanoma Similar Regardless of Race/Ethnicity

A melanoma diagnosis increases risk of a second primary melanoma regardless of race or ethnicity, a review of a government database showed.

Although white patients had the highest absolute risk for primary melanoma, Black patients had the highest relative risk of second primary melanomas, with a standardized incidence ratio (SIR) of 264.39 versus the general population. Asian/Pacific Islander patients had the second highest rate, followed by Hispanics and American Indian/Alaska Native ethnic groups.

Whites had the highest absolute rate of primary melanoma as well as the highest absolute number of excess second primary melanomas, highlighting limitations of focusing on relative risk, reported Adewole S. Adamson, MD, of the University of Texas Dell Medical School in Austin, and co-authors in JAMA Dermatology.

“To our knowledge, this study is the first to report both absolute and relative measures for risk of second primary melanoma, aligning with guideline recommendations,” the authors wrote of their findings. “While we found elevated relative risks of second primary melanoma among racial and ethnic minority groups versus the general population, measures of absolute risk were far less substantial, illustrating that reporting only relative measures, as done previously, is potentially misleading.”

Despite acknowledged limitations, “this study may inform surveillance strategies in a diverse population,” they added.

The findings highlighted the need for caution in interpreting analyses of rare events, noted the authors of an accompanying editorial.

“There is indeed a higher relative risk of second primary melanomas among Asian or Pacific Islander and Black individuals,” stated Mya L. Roberson, PhD, of the University of North Carolina Gillings School of Global Public Health in Chapel Hill, and Ivo Abraham, PhD, of the University of Arizona R. Ken Coit College of Pharmacy in Tucson. “However, the absolute incidence as well as the excess risk of second primary melanomas for these populations were orders of magnitude lower than that of second primary melanomas for white individuals.”

“These key distinctions underscore the necessity of taking into account the baseline absolute frequency of rare events when interpreting relative measures of risk.”

In the general population, a melanoma diagnosis increases the risk of a second primary melanoma by almost ninefold versus a negative melanoma history. Less certainty exists about the extent to which the risk of a second primary melanoma varies across racial and ethnic groups, Adamson and co-authors noted.

In an effort to produce data that might inform surveillance strategies, investigators queried the NCI Surveillance, Epidemiology, and End Results database to identify patients with a first primary cutaneous melanoma diagnosis from 2000 to 2019. The primary outcome was occurrence of a second primary cutaneous melanoma at least 2 months after the initial diagnosis. The analysis adhered to the Strengthening the Reporting of Observational Studies guidelines.

Adamson and colleagues estimated the risk of two primary melanomas in accordance to two hypotheses. The null hypothesis assumed that the two melanoma diagnoses occurred independent of each other. The alternative hypothesis required calculation of conditional risk (second primary melanoma conditional on having had a first primary melanoma).

The query identified 546,756 patients with a first primary melanoma diagnosis. Whites accounted for 96% of the cases, followed by Hispanics (3.1%), Asian/Pacific Islanders (0.6%), Blacks (0.4%), and American Indian/Alaska Native (0.2%).

Consistent with existing evidence, white patients had the highest absolute risk of first and second primary cutaneous melanomas (47.67/100,000 people and 1,457.40/100,000 person-years, respectively). The American Indian/Alaska Native subgroup came next (10.89/100,000 and 1,276.68/100,000), followed by Hispanics (7.10/100,000 and 959.63/100,000), Asian/Pacific Islanders (1.94/100,000 and 773.60/100,000), and Blacks (1.35/100,000 and 827.04/100,000). Similar results occurred whether calculations were based on the null or alternative hypothesis.

Calculations for relative risk presented a different picture. Black patients had the highest relative risk of second primary melanomas (SIR 264.39), followed by Asian/Pacific Islanders (SIR 196.68), Hispanics (SIR 62.71), American Indian/Alaska Native (SIR 48.47), and whites (SIR 11.63). White patients still had the highest absolute number of excess second primary melanomas (1,332.07/100,000 person-years).

“Although melanoma is less common among racial and ethnic minority populations, individuals in these groups with a first melanoma diagnosis have a rate of second primary melanoma diagnosis comparable to that of white patients,” the authors stated. “While this pattern has been observed in Black patients, it has not been explored in other disaggregated racial and ethnic groups. Findings suggest that history of a first melanoma is a risk factor for subsequent melanoma regardless of race and ethnicity.”