Assessment of Age, Period, and Birth Cohort Effects and Trends in Merkel Cell Carcinoma Incidence in the United States

Abstract

IMPORTANCE Merkel cell carcinoma is an aggressive, cutaneous, neuroendocrine cancer that is increasing in incidence. Understanding why the incidence of Merkel cell carcinoma is increasing through underlying factors, such as age effects, calendar period of diagnosis effects, and birth cohort effects, can help guide resource allocation and design of screening programs.OBJECTIVES To evaluate the associations of patient age, calendar period of diagnosis, and birth cohort with the increasing incidence of Merkel cell carcinoma and to provide new incidence projections to 2030. DESIGN, SETTING, AND PARTICIPANTSA cross-sectional retrospective study with age-period-cohort analysis and incidence projection modeling using data from the Surveillance, Epidemiology, and End Results Program database of 9 registries from 1987 to 2016 was conducted among 3720 patients with Merkel cell carcinoma. Statistical analysis was conducted from October 20, 2019, to July 29, 2020.EXPOSURES Age effects (ie, physiology), period of diagnosis effects (ie, changes in diagnostics and clinical awareness), and birth cohort effects (ie, environmental risk factors) over time were assessed. MAIN OUTCOMES AND MEASURESIncidence rates of Merkel cell carcinoma. RESULTS Among the 3720 patients in the study (2200 male patients [59.1%]; median age, 77 years [interquartile range, 68-84 years]), during the period from 2012 to 2016, the age-adjusted Merkel cell carcinoma incidence rate was 0.66 per 100 000 (95% CI, 0.62-0.70), which represented a 3.5-times (95% CI, 3.0-4.2) increase from 1987 to 1991. The incidence of Merkel cell carcinoma increased with patient age across calendar periods and birth cohorts; the highest incidence rate was observed for those aged 85 years or older, with an age-adjusted rate from 2012 to 2016 of 14.6 per 100 000 for men and 5.5 per 100 000 for women. Although the birth cohort effect has continued to increase over time, the calendar period of diagnosis effect has started to plateau. It is projected that there will be 3023 new cases of Merkel cell carcinoma in 2020 and 5130 new cases in 2030, increased from an estimated 1933 cases in 2010. CONCLUSIONS AND RELEVANCEThe slowing down of the period effect (ie, changes in diagnostics and awareness) found in this longitudinal cohort study suggests that part of the initial increased incidence of Merkel cell carcinoma was associated with increased detection. However, the projected increase in incidence rate is likely associated with the aging population and increasing risk factor exposure in more recent birth cohorts.

Merkel Cell Carcinoma: Changing Practice Patterns and Impact on Recurrence-Free and Overall Survival at a Single Institution and Nationally

“…9 While MCC is still a rare disease, its incidence continues to rise, and the United States has seen a 95% increase in the incidence from 0.5 cases per 100,000 in 2000 to 0.66 cases per 100,000 in 2016, with a predicted continued increase to 5130 cases/year by 2030. 3,10 Historically, treatment for MCC has been variable and included a combination of surgical resection of the primary with or without sentinel lymph node evaluation, radiation of the primary tumor and/or the associated lymph node basin, and chemotherapy, resulting in generally poor durable responses. 11 Recent clinical trials have demonstrated the efficacy of immunotherapy, while further defining the role of nodal staging and radiotherapy has led to improvements in treatment response.…”

Cells to Surgery Quiz: September 2021

“…Multiple recent studies have identified and predicted an increasing incidence of MCC (Jacobs et al, 2021;Paulson et al, 2018;Stang et al, 2018;Zaar et al, 2016). Stang et al ( 2018) performed an analysis of MCC incidence across 20 countries and found increasing incidence in the majority of populations studied and stable incidence rates in some others (including Denmark and Norway).…”

“…In another study of MCC incidence by Paulson et al (2018), an aging baby boomer generation was found to be driving the increasing number of new cases in the United States. In a longitudinal cohort study, Jacobs et al (2021) concluded that part of the increased incidence of MCC was due to increased detection. The increasing prevalence of immunosuppression may also be playing a role because it has been shown that MCC occurs more frequently in immunosuppressed individuals (Ma and Brewer, 2014).…”

From Merkel Cell Polyomavirus Infection to Merkel Cell Carcinoma Oncogenesis

“…Though MCC cases are rare, the incidence of MCC has tripled over the last two decades and is projected to increase further in the future (Fitzgerald et al, 2015 ; Paulson et al, 2018a ; Stang et al, 2018 ; Freeman et al, 2019 ; Jacobs et al, 2020 ). MCC has a high rate of mortality with 5-year overall survival around 51% for patients presenting with local disease at the time of diagnosis, and worse prognoses for those with more advanced stages of disease (Harms K. L. et al, 2016 ).…”