Background: The life expectancy of untreated non-small-cell lung cancer (NSCLC) is dismal, while treatment for NSCLC improves survival. The presence of comorbidities is thought to play a significant role in the decision to treat or not treat a given patient. We aim to evaluate the association of comorbidities with the survival of patients treated for NSCLC.
Methods: We performed a retrospective study of patients aged ≥66 years with invasive NSCLC between the years 2007 and 2011 in the Surveillance, Epidemiology, and End Results Kentucky Cancer Registry. Comorbidity was measured using the Klabunde Comorbidity Index (KCI), and univariate and multivariate logistic regression models were used to measure association between receiving treatment and comorbidity. Kaplan–Meier plots were constructed to estimate time-to-event outcomes.
Results: A total of 4014 patients were identified; of this, 94.9% were white and 55.7% were male. The proportion of patients who did not receive any treatment was 8.7%, 3.9%, 19.1%, and 23.5% for stages I, II, III, and IV, respectively (p<0.0001). In multivariate analysis, older age, higher stage, and higher comorbidity (KCI ≥3) were associated with a lower likelihood of receiving any treatment. The median overall survival (OS) for untreated and KCI=0 was 17.7 months for stages I and II, 2.3 months for stage III, and 1.3 months for stage IV. The median OS for treated and KCI=0 was 58.9 months for stages I and II, 16.8 months for stage III, and 5.8 months for stage IV (p<0.01). Treatment was an independent predictor of OS in multivariate analysis that included KCI scores.
Conclusion: Our data suggest that lung cancer patients may derive a survival benefit from therapies, regardless of the presence of comorbidities, although the degree of benefit seems to decrease with higher KCI scores.

Keywords: non-small-cell lung cancer, Klabunde, cancer, comorbidity index, lung cancer 


Non-small-cell lung cancer (NSCLC), when untreated, proves invariably deadly in the vast majority of patients within 1 year.1 NSCLC is diagnosed at advanced stages (III or IV) in 70% of the cases in the USA, and 19%–24% of the individuals with advanced NSCLC are never treated.2,3 Furthermore, untreated NSCLC accounts for 55% of all untreated advanced cancers in the USA.There are multiple reasons why patients do not receive therapy; however, comorbidity consistently stands out as a reported predictor for lack of therapy for NSCLC patients.4–6 Comorbidity burden has been described to be higher along with the high prevalence of smoking in lung cancer compared with other types of solid tumors.7 The presence of comorbidities can influence treatment selection due to organ damage or increased risk of adverse effects. Currently, it remains unclear if the comorbidity burden alone is predictive of outcome in a lung cancer patient or only when it affects patient’s performance status.5Similarly, there are limited data regarding the actual benefit of treating lung cancer in patients with a high comorbidity burden. In this study, we aim to evaluate the association of comorbidities with the treatment and the survival of NSCLC patient population along with the degree of benefit from treatment in those patients with comorbidities.

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Patient population and eligibility criteria

A retrospective cohort study of patients aged ≥66 years diagnosed with invasive NSCLC stages I through IV between the years 2007 and 2011 in the state of Kentucky, was performed using data from the Surveillance, Epidemiology, and End Results (SEER) registry linked to claim files from the US Medicare database (SEER-Medicare). Medicare provides insurance to elderly Americans and this study included patients who had continuous Medicare part A (hospital insurance) and part B (medical insurance) coverage 12 months prior and 6 months after lung cancer diagnosis or death, whichever came first. We excluded patients with health maintenance organization coverage in the previous 12 months, those with Medicare eligibility due to end-stage renal disease or disability, and those with a concurrent diagnosis of cancer within 3 months of lung cancer diagnosis (Figure 1). The chair granted an Institutional Review Board approval after an expedited review application at the University of Louisville, Kentucky.