Who Gets Treated for Merkel Cell Carcinoma? A Landmark Database Study Maps the Inequities

Merkel cell carcinoma is one of the rarest and most lethal skin cancers known to medicine, a neuroendocrine malignancy that kills a greater proportion of its victims than melanoma, despite accounting for less than one percent of all cutaneous cancers. Now, one of the largest analyses ever conducted on the disease has revealed that who survives this aggressive cancer depends not only on biology, but on sex, insurance status, income, ethnicity, and even the distance a patient must travel to reach a treatment center. In a nationwide study published in Archives of Dermatological Research, researchers mined the National Cancer Database to follow more than 20,000 Americans diagnosed with Merkel cell carcinoma between 2004 and 2021, and their findings expose stark inequities in both the treatments patients receive and the outcomes they ultimately achieve.

The scale of the analysis is what gives it power. The National Cancer Database, a joint program of the American College of Surgeons and the American Cancer Society, captures roughly seventy percent of all cancer cases in the United States. From a pool of 60,076 patients with cutaneous malignancies, the team identified Merkel cell carcinoma cases using the ICD-O-3 histology code 8247, ultimately assembling a final cohort of 20,078 patients after excluding records with missing demographic or treatment data. The cohort had a mean age of 76 years, was overwhelmingly male at 63.5 percent, and was racially homogeneous, with 99.8 percent of patients recorded as White. Medicare covered 75.6 percent of patients, private insurance 22.0 percent, and more than half lived in metropolitan areas of at least one million people. Surgery was performed in 84.3 percent of cases, radiation in 46.6 percent, and chemotherapy in just 10.5 percent.

Statistically, the researchers deployed two complementary modeling strategies. Multivariable binomial logistic regression was used to estimate the odds of receiving surgery, radiation, or chemotherapy, with American Joint Committee on Cancer stage included as a covariate to account for disease severity. Separately, multivariable Cox proportional hazards regression estimated hazard ratios for overall survival, the primary endpoint because cancer-specific survival is not captured in the database. Reference categories were prespecified for every variable: male sex, age under 65, White race, non-Hispanic ethnicity, uninsured status, the lowest income quartile, residence in a large metropolitan area, and travel distances under 10 miles. The results, reported as odds ratios and hazard ratios with 95 percent confidence intervals, paint a detailed portrait of how demographics and geography shape the Merkel cell carcinoma experience.

The survival findings are striking. Women had a substantially lower risk of death than men, with a hazard ratio of 0.716, meaning their mortality risk was roughly 28 percent lower even after adjustment for other factors. Asian patients showed markedly improved survival compared to White patients, with a hazard ratio of 0.312, though the authors caution that the tiny number of Asian patients in this overwhelmingly White cohort limits the precision of that estimate. Insurance type emerged as a powerful determinant of survival: compared with uninsured patients, those with private insurance had a hazard ratio of 0.565 and those with Medicare 0.730, both strongly protective. Medicaid, however, conferred no survival advantage at all, with a hazard ratio of 0.914 that was statistically indistinguishable from being uninsured.

Socioeconomic status left its own fingerprint on survival. Patients living in areas with median household incomes of $48,000 to $62,999 had a hazard ratio of 0.907, and those in areas earning $63,000 or more had a hazard ratio of 0.876, both modestly protective compared to the lowest income quartile. Educational attainment in a patient’s region, by contrast, showed no correlation with survival. Geography mattered as well: patients in smaller metropolitan areas had a hazard ratio of 1.119 and those in small urban regions 1.163, both indicating significantly worse survival than residents of large metropolitan centers. Most intriguingly, patients who traveled more than 50 miles for care had a hazard ratio of 0.786, a substantial survival benefit, while even travel of 11 to 50 miles conferred a slight advantage. The paradox that longer journeys predict longer life likely reflects the fact that patients willing and able to travel are often seeking care at high-volume, specialized academic centers.

Treatment patterns revealed their own inequities. Hispanic patients were significantly less likely than non-Hispanic patients to undergo surgery, with an odds ratio of 0.696, and less likely to receive radiation, with an odds ratio of 0.824. No significant ethnic differences appeared in chemotherapy use. Women were slightly more likely to receive surgery than men but slightly less likely to receive radiation, with an odds ratio of 0.907. Private insurance increased the likelihood of radiation, with an odds ratio of 1.530 compared to the uninsured, but insurance status showed no significant association with surgery or chemotherapy. Patients from regions with higher educational attainment were consistently more likely to receive radiation than those from the least educated quartile, suggesting that health literacy and the ability to navigate complex healthcare systems may facilitate access to guideline-based adjuvant therapy.

Age and travel distance shaped treatment in divergent ways. Chemotherapy use declined steeply with age: patients aged 65 to 79 were about half as likely to receive it as those under 65, with an odds ratio of 0.568, and patients 80 and older had markedly lower odds at 0.220. Older patients were also less likely to receive radiation, yet surgical utilization did not decline substantially with age, suggesting clinicians still pursue definitive excision in carefully selected elderly patients. Travel distance produced a fascinating split: patients traveling more than 50 miles had greater odds of surgery, at 1.247, but dramatically lower odds of chemotherapy, at 0.524, and reduced odds of radiation, at 0.737. One plausible interpretation is that distant patients consolidate care into a single definitive surgical encounter at a specialty center, while the fragmented logistics of multi-week adjuvant regimens become impractical across long distances.

Stage at diagnosis, unsurprisingly, was the strongest driver of treatment selection. Compared with patients diagnosed at Stage 0-I, those with Stage II disease had sharply reduced odds of surgery at 0.321, Stage III at 0.107, and Stage IV at a mere 0.018. The pattern reversed for chemotherapy, where Stage II patients had an odds ratio of 3.339, Stage III 10.918, and Stage IV 29.168 relative to early-stage disease. Radiation peaked at Stage III with an odds ratio of 1.653 but fell to 0.320 in Stage IV patients, reflecting the shift toward systemic therapy in metastatic disease. Notably, each modality was independently associated with reduced mortality in stage-adjusted models: surgery with a hazard ratio of 0.869, chemotherapy with 0.917, and radiation with 0.731, underscoring that access to these therapies is not merely a matter of convenience but of survival.

The authors offer several biological and structural interpretations for their findings. The female survival advantage, they suggest, may stem from differences in tumor behavior, immune response, or health-seeking behavior, and they call for molecular profiling studies to determine whether intrinsic biologic differences contribute. The null finding for Medicaid echoes melanoma research, where Medicaid coverage has been linked to delays in definitive surgery and worse survival, possibly reflecting barriers to specialty care, greater comorbidity burden, or systemic diagnostic delays. Given that Medicaid insures nearly a quarter of the US population, the authors argue that addressing barriers to timely care within this system could reduce disparities for a substantial patient group. Similarly, the lower chemotherapy use among the highest-income patients may reflect earlier substitution of immune checkpoint inhibitors, the now-preferred systemic therapy for advanced disease, which were only beginning to enter practice during the study window and accounted for just six percent of systemic treatment in this cohort.

The study’s limitations deserve honest acknowledgment. The National Cancer Database may underrepresent patients treated at non-accredited facilities, including rural and community hospitals, biasing results toward resource-rich centers. It records all-cause rather than cancer-specific mortality, potentially overestimating Merkel cell carcinoma deaths in older patients with competing comorbidities, and it lacks data on recurrence, chemotherapy regimens, radiation dosing, and treatment sequencing. The extreme racial homogeneity of the cohort, 99.8 percent White, likely enriched by the exclusion of incomplete records, underpowers race-specific estimates and may have produced false negatives for Black and Hispanic survival comparisons. Residual confounding and immortal time bias inherent to retrospective analyses may also have influenced the treatment-survival associations, and the models did not control for year of diagnosis, allowing evolving treatment trends to affect the estimates. Even so, the central message stands: in this rare but relentless cancer, survival is shaped by age, sex, insurance, income, and geography, and targeted efforts to improve access to definitive surgery and adjuvant therapy, particularly for Hispanic patients and those in underserved regions, may help dismantle the survival inequities this landmark analysis has brought into sharp focus.

Subject of Research: Demographic, socioeconomic, and geographic predictors of treatment utilization and survival in Merkel cell carcinoma

Article Title: Demographic, socioeconomic, and geographic predictors of treatment utilization and survival in Merkel cell carcinoma: an analysis of the national cancer database

Article References: Demographic, socioeconomic, and geographic predictors of treatment utilization and survival in Merkel cell carcinoma: an analysis of the national cancer database. (n.d.). https://doi.org/10.1007/s00403-026-04985-x

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04985-x

Keywords: Merkel cell carcinoma, skin cancer, National Cancer Database, health disparities, insurance status, socioeconomic status, radiation therapy, chemotherapy, surgical treatment, survival analysis, Hispanic ethnicity, geographic access