A research letter revealed significant racial and ethnic differences in the risk of developing a second primary melanoma.
In the letter, published in JAMA Dermatology, investigators analyzed data from 546,756 patients diagnosed with a first primary cutaneous melanoma between 2000 and 2019, using 17 Surveillance, Epidemiology, and End Results (SEER) registries.
The investigators found that while White patients had the highest absolute incidence of both first and second primary melanomas, Black patients faced the highest relative risk of developing a second primary melanoma compared with the general population. The standardized incidence ratio (SIR) among Black patients was 264.39 (95% confidence interval [CI] = 211.48–326.52), followed by Asian or Pacific Islander patients at 196.68 (95% CI = 165.45–232.09), and Hispanic patients at 62.71 (95% CI = 58.58–67.06).
When examining excess absolute risks (EARs), White patients had the highest number of excess second primary melanomas per 100,000 person-years at 1,332.07 (95% CI = 1,318.68–1,345.55).
The methodology involved calculating SIRs by dividing observed cases by expected cases, with expected numbers calculated by applying sex-, attained age-, race-, ethnicity-, and attained calendar year–specific incidence rates to the accumulated person-years of observation. EARs were calculated as the difference between observed and expected cases per 100,000 person-years of follow-up.
The letter reported on two hypotheses used to estimate the risk of developing two primary melanomas. The null hypothesis assumed that first and second melanoma diagnoses were independent events with identical risk, whereas the alternative hypothesis calculated conditional risk more directly by multiplying the risk of a second melanoma conditional on having had a first melanoma.
Incidence rates of first primary melanoma per 100,000 individuals varied significantly across racial and ethnic groups:
- White: 47.67 (95% CI = 47.54–47.80)
- American Indian or Alaska Native: 10.89 (95% CI = 10.23–11.58)
- Hispanic: 7.10 (95% CI = 6.98–7.21)
- Asian or Pacific Islander: 1.94 (95% CI = 1.87–2.01)
- Black: 1.35 (95% CI = 1.29–1.41).
The incidence of second primary melanoma among patients with a prior melanoma diagnosis per 100,000 person-years also showed substantial variation:
- White: 1,457.40 (95% CI = 1,444.01–1,470.88)
- American Indian or Alaska Native: 1,276.68 (95% CI = 1,015.38–1,584.69)
- Hispanic: 959.63 (95% CI = 896.41–1,026.13)
- Black: 827.04 (95% CI = 661.52–1,021.38)
- Asian or Pacific Islander: 773.60 (95% CI = 650.76–912.87).
Limitations noted in the letter included the potential misclassification of recurring previous melanoma as a second primary melanoma and the potential for surveillance bias to overestimate differences across groups.
The investigators emphasized the importance of reporting both absolute and relative measures for the risk of second primary melanoma, aligning with guideline recommendations. They noted that while elevated relative risks were found among racial and ethnic minority groups compared with the general population, measures of absolute risk were less substantial.
Conflict of interest disclosures can be found in the letter.