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Effects of Comorbidity and Smoking on the Survival of Lung Cancer Patients

Department of Internal Medicine, Social and Preventive Medicine, College of Medicine, Inha University, Incheon, South Korea

To the Editor:

The article "Never-Smokers With Lung Cancer: Epidemiologic Evidence of a Distinct Disease Entity" by Toh et al¹ recently published in the Journal of Clinical Oncology was of great interest to us. They reported that non–small-cell lung cancer of the never smoker is different from the non–small-cell lung cancer of the ever smoker in terms of epidemiologic features as well as survival.

Recent advances in cancer treatment, especially molecular targeting agents, have led to greater interest in better understanding epidemiologic factors, such as sex and ethnic differences, as well as smoking effects. Smoking is well known to have a major role in the carcinogenesis and progression of lung cancer. Therefore, it is not surprising that a never-smoker would have different characteristics from an ever-smoker even in survival. In this regard, the never-smoker was shown to have a longer survival in retrospective hospital-based cancer cohorts.^1-3

However, despite the interesting observation by Toh et al,¹ it is unclear why the presence of comorbidity was not associated with survival and smoking status. Some comorbidities, such as cardiovascular disease or chronic obstructive pulmonary disease which can act as potential hazards when providing appropriate treatment to lung cancer patients, have been shown to be clearly attributable to smoking. However, no difference in comorbidity was noted between never-smokers and ever-smokers in the study by Toh et al.¹ Severity or burden of comorbid factors has been reported to have a clear relationship with poor survival in a variety of cancer patients.⁴ Careful evaluation and assessment of the severity of comorbidity is an essential part for verifying the prognostic relevance.⁵ Therefore, the retrospective hospital-based cancer cohort has significant limitations in this regard. Furthermore, the effect of comorbidity on the survival of lung cancer patients is expected to become more important as survival continues to improve.

In addition, there was substantial evidence that comorbidities from smoking were significantly related to the poor survival of lung cancer patients.^6,7 A prospective cohort study with a large populations needs to answer the following questions: do comorbidities or their severity interact with smoking to affect the survival of lung cancer patients? Does smoking and comorbidities, especially those related to smoking, affect survival independently or are they confounding as one? It is time to address the issue of evaluating comorbidities in patients with lung cancer.

Authors' Disclosures of Potential Conflicts of Interest

The authors indicated no potential conflicts of interest.

ACKNOWLEDGMENTS

This study was supported by Inha University research grant.

REFERENCES

1. Toh CK, Gao F, Lim WT, et al: Never-smokers with lung cancer: Epidemiologic evidence of a distinct disease entity. J Clin Oncol 24:2245-2251, 2006[Abstract/Free Full Text]

2. Sardari Nia P, Weyler J, Colpaert C, et al: Prognostic value of smoking status in operated non-small cell lung cancer. Lung Cancer 47:351-359, 2005[CrossRef][Medline]

3. Nordquist LT, Simon GR, Cantor A, et al: Improved survival in never-smokers vs current smokers with primary adenocarcinoma of the lung. Chest 126:347-351, 2004[CrossRef][Medline]

4. Piccirillo JF, Tierney RM, Costas I, et al: Prognostic importance of comorbidity in a hospital-based cancer registry. JAMA 291:2441-2447, 2004[Abstract/Free Full Text]

5. Yancik R, Ganz PA, Varricchio CG, et al: Perspectives on comorbidity and cancer in older patients: Approaches to expand the knowledge base. J Clin Oncol 19:1147-1151, 2001[Abstract/Free Full Text]

6. Lopez-Encuentra A, Astudillo J, Cerezal J, et al: Bronchogenic Carcinoma Cooperative Group of the Spanish Society of Pneumology and Thoracic Surgery (GCCB-S): Prognostic value of chronic obstructive pulmonary disease in 2994 cases of lung cancer. Eur J Cardiothorac Surg 27:8-13, 2005[Abstract/Free Full Text]

7. Eberly LE, Ockene J, Sherwin R, et al: Intervention Trial Research Group: Pulmonary function as a predictor of lung cancer mortality in continuing cigarette smokers and in quitters. Int J Epidemiol 32:592-599, 2003[Abstract/Free Full Text]

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This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Save to my personal folders Download to citation manager Rights & Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ryu, J.-S. Articles by Lee, H.-J. Search for Related Content PubMed PubMed Citation Articles by Ryu, J.-S. Articles by Lee, H.-J. Social Bookmarking                            What's this?