Merkel Cell Carcinoma: Incidence, Mortality, and Risk of Other Cancers
Merkel Cell Carcinoma: Incidence, Mortality, and Risk of Other Cancers
Background Merkel cell carcinoma (MCC) is a rare skin cancer that was recently found to be associated with a polyomavirus and with immunosuppression, provoking new interest in its epidemiology. We conducted a nationwide study in Denmark to describe MCC incidence and mortality and the association between MCC and other cancers.
Methods We used data from Danish national health and population registers on MCC diagnoses, deaths, and population counts during the study period (1978–2006) to calculate MCC incidence rates, cumulative risks of MCC at age 100 years, and MCC mortality rates by tumor stage. We used Poisson regression to estimate the excess mortality rate ratio attributable to MCC and examined associations between MCC and other cancers diagnosed before and after the MCC diagnosis using standardized incidence rate ratios (SIRs). All statistical tests were two-sided.
Results Between January 1, 1978, and December 31, 2006, 185 persons were diagnosed with MCC in Denmark. MCC incidence between 1995 and 2006 was 2.2 cases per million person-years. In the first year after MCC diagnosis, 22% of persons with localized disease died compared with 54% of patients with nonlocalized disease; by 5 years after diagnosis, the proportions of MCC patients who had died increased to 55% and 84%, respectively. MCC incidence was statistically significantly increased more than 1 year after a diagnosis of squamous cell carcinoma of the skin (SIR = 14.6, 95% confidence interval [CI] = 8.4 to 25.6), basal cell carcinoma (SIR = 4.3, 95% CI = 2.7 to 6.6), malignant melanoma (SIR = 3.3, 95% CI = 1.1 to 10.3), chronic lymphocytic leukemia (SIR = 12.0, 95% CI = 3.8 to 37.8), Hodgkin lymphoma (SIR = 17.6, 95% CI = 2.5 to 126), and non-Hodgkin lymphoma (SIR = 5.6, 95% CI = 1.4 to 22.4). Squamous cell carcinoma (SIR = 12.1, 95% CI = 5.1 to 29.1) and chronic lymphocytic leukemia (SIR = 14.7, 95% CI = 3.7 to 58.8) occurred in statistically significant excess more than 1 year after MCC diagnosis.
Conclusions These results support the existence of shared risk factors for MCC and other cancers. Heightened awareness of the association between MCC and other cancers, particularly squamous cell carcinoma and chronic lymphocytic leukemia, may facilitate earlier clinical detection and treatment of MCC, thereby improving patient survival.
Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer that occurs more frequently in immunosuppressed individuals, such as those infected with HIV and/or diagnosed with AIDS. In 2008, a previously unknown polyomavirus designated Merkel cell polyomavirus (MCV) was found in MCC tumors; MCV DNA sequences were detected in eight (80%) of the 10 MCC tumors compared with only four (16%) of the 25 control skin tissue samples.
Many individuals who are diagnosed with MCC have a history of other sun exposure–associated skin cancers, and MCC may also share etiologic factors with other malignancies. For example, increased joint risks of MCC and multiple myeloma, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and malignant melanoma have been reported but have not been explained.
These findings have provoked a new interest in the epidemiology of MCC and in investigating the co-occurrence of MCC and other cancers. In this study, we used Danish national health and population registers to examine MCC incidence, MCC mortality by stage at diagnosis, and the association between MCC and the risk of other cancers, particularly the risks of basal cell carcinoma and squamous cell carcinoma of the skin before and after MCC diagnosis.
Abstract and Introduction
Abstract
Background Merkel cell carcinoma (MCC) is a rare skin cancer that was recently found to be associated with a polyomavirus and with immunosuppression, provoking new interest in its epidemiology. We conducted a nationwide study in Denmark to describe MCC incidence and mortality and the association between MCC and other cancers.
Methods We used data from Danish national health and population registers on MCC diagnoses, deaths, and population counts during the study period (1978–2006) to calculate MCC incidence rates, cumulative risks of MCC at age 100 years, and MCC mortality rates by tumor stage. We used Poisson regression to estimate the excess mortality rate ratio attributable to MCC and examined associations between MCC and other cancers diagnosed before and after the MCC diagnosis using standardized incidence rate ratios (SIRs). All statistical tests were two-sided.
Results Between January 1, 1978, and December 31, 2006, 185 persons were diagnosed with MCC in Denmark. MCC incidence between 1995 and 2006 was 2.2 cases per million person-years. In the first year after MCC diagnosis, 22% of persons with localized disease died compared with 54% of patients with nonlocalized disease; by 5 years after diagnosis, the proportions of MCC patients who had died increased to 55% and 84%, respectively. MCC incidence was statistically significantly increased more than 1 year after a diagnosis of squamous cell carcinoma of the skin (SIR = 14.6, 95% confidence interval [CI] = 8.4 to 25.6), basal cell carcinoma (SIR = 4.3, 95% CI = 2.7 to 6.6), malignant melanoma (SIR = 3.3, 95% CI = 1.1 to 10.3), chronic lymphocytic leukemia (SIR = 12.0, 95% CI = 3.8 to 37.8), Hodgkin lymphoma (SIR = 17.6, 95% CI = 2.5 to 126), and non-Hodgkin lymphoma (SIR = 5.6, 95% CI = 1.4 to 22.4). Squamous cell carcinoma (SIR = 12.1, 95% CI = 5.1 to 29.1) and chronic lymphocytic leukemia (SIR = 14.7, 95% CI = 3.7 to 58.8) occurred in statistically significant excess more than 1 year after MCC diagnosis.
Conclusions These results support the existence of shared risk factors for MCC and other cancers. Heightened awareness of the association between MCC and other cancers, particularly squamous cell carcinoma and chronic lymphocytic leukemia, may facilitate earlier clinical detection and treatment of MCC, thereby improving patient survival.
Introduction
Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer that occurs more frequently in immunosuppressed individuals, such as those infected with HIV and/or diagnosed with AIDS. In 2008, a previously unknown polyomavirus designated Merkel cell polyomavirus (MCV) was found in MCC tumors; MCV DNA sequences were detected in eight (80%) of the 10 MCC tumors compared with only four (16%) of the 25 control skin tissue samples.
Many individuals who are diagnosed with MCC have a history of other sun exposure–associated skin cancers, and MCC may also share etiologic factors with other malignancies. For example, increased joint risks of MCC and multiple myeloma, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and malignant melanoma have been reported but have not been explained.
These findings have provoked a new interest in the epidemiology of MCC and in investigating the co-occurrence of MCC and other cancers. In this study, we used Danish national health and population registers to examine MCC incidence, MCC mortality by stage at diagnosis, and the association between MCC and the risk of other cancers, particularly the risks of basal cell carcinoma and squamous cell carcinoma of the skin before and after MCC diagnosis.
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