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International Journal of Breast Cancer
Volume 2014, Article ID 970780, 11 pages
Research Article

Impact of Undetected Comorbidity on Treatment and Outcomes of Breast Cancer

1Nuffield Department of Primary Care Health Sciences, University of Oxford, 23-38 Hythe Bridge Street, 2nd Floor, Oxford OX1 2ET, UK
2Division of General Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
3Outcomes Insights, 340 North Westlake Blvd, Suite 200, Westlake Village, CA 91362, USA

Received 10 October 2013; Accepted 6 January 2014; Published 13 February 2014

Academic Editor: Ian S. Fentiman

Copyright © 2014 Robert I. Griffiths et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Preexisting comorbidity adversely impacts breast cancer treatment and outcomes. We examined the incremental impact of comorbidity undetected until cancer. We followed breast cancer patients in SEER-Medicare from 12 months before to 84 months after diagnosis. Two comorbidity indices were constructed: the National Cancer Institute index, using 12 months of claims before cancer, and a second index for previously undetected conditions, using three months after cancer. Conditions present in the first were excluded from the second. Overall, 6,184 (10.1%) had undetected comorbidity. Chronic obstructive pulmonary disease (38%) was the most common undetected condition. In multivariable analyses that adjusted for comorbidity detected before cancer, older age, later stage, higher grade, and poor performance status all were associated with higher odds of undetected comorbidity. In stage I–III cancer, undetected comorbidity was associated with lower adjusted odds of receiving adjuvant chemotherapy (Odds Ratio (OR) = 0.81, 95% Confidence Interval (CI) 0.73–0.90, ; , 95% CI 0.30–0.49, ; index score 1 or , respectively), and with increased mortality (Hazard Ratio (HR) = 1.45, 95% CI 1.38–1.53, ; , 95% CI 2.18–2.60, ; index score 1 or ). Undetected comorbidity is associated with less aggressive treatment and higher mortality in breast cancer.