Merkel cell carcinoma data for patients in Miami, Florida: A retrospective analysis

Inadequate literature has analyzed Merkel cell carcinoma (MCC) in ethnically diverse Hispanic and Black populations. Considering the rising proportion of MCC in such minority groups¹ and the racial and ethnic heterogeneity of Miami-Dade County, we reviewed MCC data for patients in Miami, Florida.

In this study, approved by the University of Miami Institutional Review Board, electronic medical records of 191 patients seen at the Sylvester Comprehensive Cancer Center at the University of Miami Miller School of Medicine from January 2010 to February 2023 were examined retrospectively by two reviewers, P. V. W. and C. D.-E. The χ² tests of independence and goodness-of-fit were used to verify any statistical significance between the observed and expected MCC rates in this patient group (p < 0.05).

Patient demographics and variables are examined in Tables 1 and 2, respectively. Of the 191 patients diagnosed with MCC, most patients (178 of the 191 or 93%) were White; of which 56 or 31% where White Hispanic. Seventy-one percent (136) were men and 81% (155) were over the age of 60 years old. The median time from symptom onset to diagnosis was 98 days. Significantly more tumours were located on the face/head/neck than on the trunk or limbs (p = 0.00). At diagnosis, most tumours were stage I or stage III (p = 0.00) and small (size ≤ 2 cm, p = 0.00). MCC was more common in men than in women, with differences in stage at diagnosis (p = 0.03) and regional lymph node status (p = 0.01) between the two sexes also being significant. Women were more likely to present at a lower stage and negative regional lymph node status, signifying nonmetastatic disease. Out of the 126 patients with known primary or secondary MCC, a significant majority (96 of 126 or 76.2%) had primary MCC. Most patients (132 of 187 or 70.6%) were also referred from another facility for treatment (p = 0.00) and had no other concurrent malignancy (110 of 165 or 66.7%, p = 0.00).

These results illustrate characteristics of MCC in a distinct, regionally Hispanic-predominant population. About one-third of the study population identified as Hispanic, and the majority of tumours were located on anatomical sites regularly exposed to sunlight. Although identification with an ethnic or racial group can be impacted by factors like skin colour, generational status and geographical nativity,² our results suggest that actinic damage likely influences the development of MCC even in Hispanic populations. Moreover, most women in our cohort had nonmetastatic disease at presentation while most men had metastatic disease at presentation, suggesting possible delay in diagnosis, preferential referral to the University or more aggressive biology in men. It is known that MCC is a highly aggressive tumour, with metastasis being associated with lower survival rates and poorer outcomes.³ These findings align with recently published data showing women have improved survival.⁴ Interestingly, however, the range of time from symptom onset to diagnosis (20–638 days) was less than that of other tertiary care centres with similar published data.⁵

Although polyomavirus status in the study population was not found to be statistically significant, only about 25% (47 of 191) of our cohort underwent Merkel cell polyomavirus (MCPyV) testing. A total of 26 of these 47 patients (55.3%) were found to be virus-negative as compared to prior studies confirming MCPyV+ status in approximately 80% of cases.^{6, 7} Because MCPyV+ tumours have a better prognosis than MCPyV− tumours, identifying viral status is essential for prognostic predictability,⁷ especially in populations more likely to have sun-protected dark skin like Hispanic and Black patients. UV-driven versus virus-positive MCC prognostic data is still lacking for these populations even in large cohort studies,^{4, 8} and future studies are needed to see how viral status affects their MCC-specific survival.

Study conception and design, data interpretation, and draft manuscript preparation were performed by Kayla D. Mashoudy. Data analysis and interpretation and material preparation were performed by Anil Dalling. Data collection was done by Caitlin Dowell-Esquivel and Peyton V. Warp. Robert S. Kirsner commented on previous versions of the manuscript and reviewed the final manuscript. All authors reviewed the results and approved the final version of the manuscript.

The authors declare no conflict of interest.

This study was reviewed and approved by the University of Miami Institutional Review Board; approval #20230362. This material is the authors' own original work, which has not been previously published elsewhere.