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Completeness of TNM cancer staging for melanoma in the Danish Cancer Registry, 2004–2009

Authors Froeslev T, Grann AF, Olsen, Olesen, Smith H, Friis S, Søgaard M

Received 21 March 2012

Accepted for publication 18 April 2012

Published 17 August 2012 Volume 2012:4(Supplement 2 Cancer staging) Pages 5—10


Review by Single anonymous peer review

Peer reviewer comments 2

Trine Frøslev,1 Anne Fia Grann,1 Morten Olsen,1 Anne Braae Olesen,1,2 Henrik Schmidt,3 Søren Friis,4 Mette Søgaard1,5

Department of Clinical Epidemiology, 2Department of Dermatology, 3Department of Oncology, Aarhus University Hospital, Aarhus, 4Danish Cancer Society Research Center, Danish Cancer Society, Copenhagen, 5Department of Clinical Microbiology, Aalborg Hospital, Aarhus University Hospital, Denmark

Background: The purpose of this study was to investigate the completeness of TNM (Tumor, Node, Metastasis) staging of melanoma in the Danish Cancer Registry (DCR).
Methods: We identified 8762 patients with a first primary diagnosis of melanoma from the DCR between 2004 and 2009. We obtained information on level of comorbidity, defined according to the Charlson Comorbidity Index, through the Danish National Patient Register. We computed the completeness of TNM staging overall and by each stage component. Analyses were stratified by gender, age, year of diagnosis, and level of comorbidity. We designed an algorithm that categorized melanoma stage as localized, regional, distant, or unknown. Owing to knowledge on clinical coding practice, we allowed for categorization of tumors with certain missing stage components.
Results: The overall completeness of the TNM staging was 78.4% (95% confidence interval [CI] 77.5–79.3). Completeness varied little by gender and year of diagnosis. However, completeness decreased from 83.5% (95% CI 81.7–85.3) in patients aged 0–39 years to 68.7% (95% CI 65.7–71.6%) in patients 80 years or older, and from 80.3% (95% CI 79.4–81.3) among patients with a low level of comorbidity to 67.4% (95% CI 63.1–71.4) among patients with a high level of comorbidity. Using the algorithm, 87.3% of cases could be assigned to one of the defined stage categories.
Conclusion: The overall completeness of the TNM registration for melanoma was fairly high but varied with age and level of comorbidity. Thus, data on TNM stage should be used with caution in epidemiological and other research.

Keywords: melanoma, neoplasm staging, TNM, Denmark

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