Differences in Merkel Cell Carcinoma Presentation and Outcomes Among Racial and Ethnic Groups

Abstract

Importance: Racial and ethnic differences in skin cancer outcomes are understudied. Delineating these differences in Merkel cell carcinoma (MCC) is needed to better understand this rare disease.

Objective: To determine how MCC presentation and outcomes differ across racial and ethnic groups.

Design, setting, and participants: This retrospective cohort study included patients diagnosed with MCC and followed up from 2000 through 2018 in the 18 population-based cancer registries of the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. Patients without follow-up data were excluded. Data analysis occurred from March 12 to November 30, 2022.

Main outcomes and measures: A Cox proportional hazards regression was conducted to determine associations between demographic variables (race and ethnicity, age, sex, and income) and clinical variables (stage at diagnosis, primary site, and diagnosis year) with MCC-specific survival.

Results: Of the 9557 patients with MCC identified (6758 [70.7%] aged ≥70 years; 6008 [62.9%] male), 222 (2.3%) were Asian American or Pacific Islander, 146 (1.5%) Black, 541 (5.7%) Hispanic, and 8590 (89.9%) White. Hispanic patients had improved MCC-specific survival compared with White patients (hazard ratio, 0.82; 95% CI, 0.67-0.99; P = .04). Black patients had the lowest MCC-specific survival, but it was not statistically different from White patients (hazard ratio, 1.19; 95% CI, 0.86-1.60; P = .28). Hispanic and Black patients were less likely to present with a primary site of the head and neck than White patients (183 of 541 [33.8%] Hispanic patients and 45 of 146 [30.8%] Black patients vs 3736 of 8590 [43.5%] White patients; P < .001 and P = .002, respectively). Black patients presented more often than White patients with advanced disease at diagnosis (59 of 146 [40.4%] vs 2510 of 8590 [29.2%]; P = .004).

Conclusions and relevance: In this cohort study, there were differences between racial and ethnic groups in observed MCC outcomes and disease characteristics. Further investigations are warranted into the findings that, compared with White patients, Hispanic patients with MCC had improved outcomes and Black patients did not have worse outcomes despite presenting with more advanced disease.

Figure 1.. Merkel Cell Carcinoma (MCC)-Specific Survival by Race and Ethnicity

A, Aggregate proportion of MCC cases by race and ethnicity. The other category was combined owing to small sample sizes and includes American Indian or Alaska Native patients and patients of non-Hispanic unknown race. B, Kaplan-Meier estimate of MCC-specific survival by race and ethnicity. P values are pairwise comparison with White patients, and P < .05 denotes statistical significance. AAPI indicates Asian American or Pacific Islander; DSS, disease-specific survival.

Figure 2.. Multivariate Associations Among Demographic and Clinical Variables and Merkel Cell Carcinoma (MCC)-Specific Survival (N = 9557)

The other race and ethnicity category was combined owing to small sample sizes and includes American Indian or Alaska Native patients and patients of non-Hispanic unknown race. AAPI indicates Asian American or Pacific Islander. P < .05 denotes statistical significance.