DISCUSSION

Our study confirms the previously reported association between the presence of comorbidities and lower likelihood of receiving cancer treatment.4–6 However, conflicting data were found with regard to the association between comorbidities and on survival of lung cancer patients. Luchtenborg et al9found that severe comorbidity had a large detrimental impact on the survival of lung cancer patients who undergo curative lung resection. In contrast, a retrospective cohort study from the Netherlands showed that the negative effect of comorbidity on survival in nonsurgical candidates was present only in patients treated with chemotherapy.10 In an analysis of all cancer cases diagnosed between 1992 and 2005 included in the US SEER database, Edwards et al7 found that the influence of comorbidities on the probability of both cancer-specific and non-cancer-related mortality was smaller for lung cancer compared with other cancers. Our study adds to the body of evidence suggesting that comorbidities influence physicians’ decision to recommend treatment for NSCLC, and that comorbidity levels may correlate with other clinical factors influencing treatment choices, such as performance status.

Despite the role of comorbidity assessments in the choice of treatments, limited data are available about the actual benefit of lung cancer therapy in patients with high comorbidity burden. Patients who are more sick are more likely to be excluded from standard clinical trials, leaving clinicians with little objective assessments of treatment benefits in the setting of high comorbidities. Furthermore, when considering the toxicity profile of chemotherapy, the intensity of treatment is limited by organ function, which can be directly impacted by the presence of comorbidities. Patients with higher burden of comorbidities, as determined by KCI score of 3 or higher, constituted ~15% of our study population. In this group, we observed significantly higher survival among those individuals who received any cancer-specific therapy compared with their equally comorbid counterparts who did not. Although selection bias could have resulted in overestimated measures of treatment effects in this observational study, our data indicate that patients may still derive a survival benefit from cancer treatments in the presence of high comorbidity. Likewise, we recognize that comorbidity is not a sole factor used to decide against treatment in NSCLC patients.


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Not all comorbid conditions are expected to have an equal impact on the treatment. The most common comorbidities in lung cancer patients are chronic obstructive pulmonary disease, coronary artery disease, congestive heart failure, diabetes, and renal insufficiency.4–6 Cardiac comorbidity and chronic obstructive pulmonary disease have been described as independent risk factors affecting the development of toxicity and the effectiveness of cancer therapy.11–13 In contrast, no clear role has been described for other comorbidities (such as liver disease or Alzheimer’s dementia) that are also included in the construction of the KCI. Moving forward, it is important for health care providers and patients to realize that, with newer therapeutic options such as immunotherapy, organ dysfunction and the comorbidity burden should play a lesser role in the decision to treat lung cancer.

There are several limitations to our analysis. The data set is from 2007 to 2011 and may not reflect more current practice patterns. This is particularly important since the recent development of immunotherapy, which is believed to have a more favorable safety profile and might not be affected by comorbidities compared with the safety profile of cytotoxic chemotherapy. Given that the study population is restricted to Kentucky residents, the results may not be generalizable to the US NSCLC population.14–19 The SEER-Medicare database does not provide data on other clinically relevant prognostic factors, including performance status and weight loss, or nonclinical factors, such as access to care and social support. The lack of ability to account for the potential confounding effect of these factors could have biased our results.

CONCLUSION

NSCLC patients with higher comorbidity burden are less likely to receive cancer-specific treatment and more likely to die. However, it appears that even in individuals with high comorbidity burden, cancer-specific treatments seem to improve survival, independently of their stage at presentation. The treatment benefit observed in the high comorbid population is likely a result of multiple factors, including the treatment itself. The impact of comorbidity along with performance status, medical and social support system, and the presenting stage play an important role in decision to treat lung cancer.

Acknowledgment

This study was supported by Kentucky Lung Cancer Education and Survivorship Grant (LEADS).

Disclosure

The authors report no conflicts of interest in this work.


Jorge Rios,1 Rahul Gosain,1 Bernardo HL Goulart,2 Bin Huang,3 Margaret N. Oechsli,1 Jaclyn K. McDowell,4 Quan Chen,4 Thomas Tucker,4 Goetz H. Kloecker1

1James Graham Brown Cancer Center, University of Louisville, Louisville, KY, 2Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA, 3Department of Biostatistics, College of Public Health, University of Kentucky, Lexington, KY, 4Markey Cancer Center, University of Kentucky, Lexington, KY, USA 


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Source: Cancer Management and Research.

Originally published January 24, 2018.