title: Joint occurrence of Merkel cell carcinoma and non-Hodgkin lymphomas in four Nordic countries.
abstract: The objective of this study was to assess the reciprocal association between non-Hodgkin lymphoma (NHL) and Merkel cell carcinoma (MCC) using the data of four Nordic Cancer Registries. Data for this study were drawn from the Danish, Finnish, Norwegian, and Swedish cancer registries. Standardized incidence ratios (SIRs) for MCC among NHL patients, and for NHL among MCC patients, were calculated. There were 109 838 individuals with NHL and 1411 individuals with MCC, of which 28 had joint occurrence of NHL and MCC. In 18 cases, NHL was diagnosed first, and in 10 cases, MCC was diagnosed first. The SIR for MCC after NHL was 4.34 (95% confidence interval 2.57-6.85). The SIR for NHL after MCC was 3.13 (1.50-5.77). Although the absolute frequency of joint occurrence of MCC and NHL is low, individuals suffering from one of the cancer forms have an increased risk of the other.
authors.affiliation: a Department of Plastic Surgery , University of Helsinki and Helsinki University Hospital , Helsinki , Finland.
authors.forename: Virve
authors.initials: V
authors.lastname: Koljonen
authors.affiliation: b Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research , Helsinki , Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Rantanen
authors.affiliation: c Department of Pathology , University of Helsinki and Helsinki University Hospital , Helsinki , Finland.
authors.forename: Helka
authors.initials: H
authors.lastname: Sahi
authors.affiliation: d Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Mellemkjær
authors.affiliation: e Department of Research , Cancer Registry of Norway , Oslo , Norway.
authors.forename: Bo Terning
authors.initials: BT
authors.lastname: Hansen
authors.affiliation: f Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ) , Heidelberg , Germany.
authors.forename: Tianhui
authors.initials: T
authors.lastname: Chen
authors.affiliation: f Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ) , Heidelberg , Germany.|g Center for Primary Health Care Research, Lund University , Malmö , Sweden.
authors.forename: Kari
authors.initials: K
authors.lastname: Hemminki
authors.affiliation: b Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research , Helsinki , Finland.|h School of Health Sciences, University of Tampere , Tampere , Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008228:Lymphoma, Non-Hodgkin / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology*; D011159:Population Surveillance; D012042:Registries; D012537:Scandinavian and Nordic Countries / Q000453:epidemiology; D012878:Skin Neoplasms / Q000453:epidemiology*
keywords: Merkel cell carcinoma; SIR; non-Hodgkin lymphoma; simultaneous