Completeness of TNM staging of small-cell and non-small-cell lung cancer in the Danish Cancer Registry, 2004–2009
Received 26 April 2012
Accepted for publication 1 June 2012
Published 17 August 2012 Volume 2012:4(Supplement 2 Cancer staging) Pages 39—44
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Thomas Deleuran,1,2 Mette Søgaard,1,3 Trine Frøslev,1 Torben Riis Rasmussen,4 Henrik Kirstein Jensen,5 Søren Friis,6 Morten Olsen1
1Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; 2Department of Medicine V (Hepatology and Gastroenterology), Aarhus University Hospital, Aarhus, Denmark; 3Department of Clinical Microbiology, Aalborg Hospital, Aarhus University Hospital, Aalborg Denmark; 4Department of Respiratory Medicine, Aarhus University Hospital, Aarhus, Denmark; 5Department of Respiratory Medicine, Aalborg Hospital, Aarhus University Hospital, Denmark; 6Danish Cancer Society Research Center, Danish Cancer Society, Copenhagen, Denmark
Objective: We examined the completeness of TNM staging of small-cell (SCLC) and non-small-cell (NSCLC) lung cancer in the national Danish Cancer Registry (DCR) and whether staging varied by year of diagnosis, gender, age, degree of comorbidity, or presence of histopathological diagnosis.
Methods: We identified all patients with SCLCs and NSCLCs registered in the DCR during 2004–2009 and examined the completeness of their TNM registrations. Completeness was defined as the number of recorded individuals with TNM divided by the total number of patients. Completeness was calculated for TNM, T, N, and M individually, overall, and by year of diagnosis, gender, age at diagnosis, and comorbidity. Data regarding comorbidity was obtained from the Danish National Patient Register (DNPR). We performed separate analyses for patients with a histopathologically verified diagnosis of NSCLC. Finally, we designed an algorithm to categorize tumors with missing TNM components as limited, extensive, or distant disease.
Results: Overall TNM staging completeness was 77.5% (95% confidence interval (CI): 76.1%–78.8%) for SCLC and 77.9% (95% CI: 77.3%–78.4%) for NSCLC. Completeness did not vary by gender and increased during the study period. The proportion of staged patients was lower among patients above 80 years of age or with medium to high levels of comorbidity.
Conclusion: Overall TNM completeness for SCLC and NSCLC in the Danish Cancer Registry is high, but decreases with increasing levels of comorbidity and at ages greater than 80 years. Researchers should be aware of these potential sources of bias.
Keywords: cancer registers, cancer staging, completeness, lung cancer
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