Epidemiology of Merkel Cell Polyomavirus Infection and Merkel Cell Carcinoma

Abstract

Merkel cell polyomavirus (MCPyV) is a ubiquitous virus replicating in human dermal fibroblasts. MCPyV DNA can be detected on healthy skin in 67–90% of various body sites, and intact virions are regularly shed from the skin. Infection occurs early in life, and seropositivity increases from 37 to 42% in 1- to 6-year-olds to 92% in adults. Merkel cell carcinoma (MCC) is a rare but very aggressive neuroendocrine tumor of the skin. It develops mainly on sun-exposed areas as a fast-growing, reddish nodule. Two MCC entities exist: about 80% of MCC are MCPyV-associated. Tumorigenesis is driven by viral integration into the host genome and MCPyV oncogene expression. In MCPyV-negative MCC, UV radiation causes extensive DNA damage leading to the deregulation of the cell cycle. In recent decades, MCC incidence rates have increased worldwide, e.g., in the United States, from 0.15 in 1986 to 0.7/100,000 in 2016. Risk factors for the development of MCC include male sex, older age (>75 years), fair skin, intense UV exposure, and immunosuppression. Projections suggest that due to aging populations, an increase in immunosuppressed patients, and enhanced UV exposure, MCC incidence rates will continue to rise. Early diagnosis and prompt treatment are crucial to reducing high MCC morbidity and mortality.

Current Progress in Vaccines against Merkel Cell Carcinoma: A Narrative Review and Update

“…Merkel cell carcinoma (MCC) is a rare type of skin cancer that mainly affects older and/or immunosuppressed individuals [41,42]. In recent decades, however, the incidence rates of MCC have ascended worldwide; for example, in the United States, from 0.15 in 1986 to 0.7/100,000 in 2016.…”

“…The risk factors for the development of MCC include male sex, age over 75 years, fair skin complexion, ultraviolet (UV) exposure, and immunosuppression. Projections propose that, due to aging populations, an increase in immunosuppressed patients, and enhanced UV exposure, MCC incidence rates will continue to rise [41].…”

A review of Merkel cell carcinoma

“…Patients who are MCV-negative have a higher recurrence rate of MCC than those who are MCV-positive 20. Despite MCV's association with MCC, it also is found in 67% to 90% of healthy human dermal fibroblasts across the entire body as part of the normal dermal flora 21…”

“…20 Despite MCV's association with MCC, it also is found in 67% to 90% of healthy human dermal fibroblasts across the entire body as part of the normal dermal flora. 21 MCC is a more aggressive type of skin cancer than BCC, SCC, or melanoma. 13 MCC more frequently develops in patients with immunocompromise, who account for about 10% of patients with MCC.…”

An Epidemiological Look into Disparities in Merkel Cell Carcinoma Hospitalizations in the United States

“…Approximately one in three individuals diagnosed with MCC die from their disease, making MCC more lethal than malignant melanoma [2]. The United States alone has seen a rise in MCC mortality rates from 0.03 to 0.43 from 1986 to 2011 [3]. Additionally, the incidence rate of MCC in the United States has increased from 0.5 to 0.7 cases per 100,000 from 2000 to 2013, with a projected continued increase among at-risk populations 4 .…”