Chest
Volume 126, Issue 2, August 2004, Pages 347-351
Journal home page for Chest

Clinical Investigations
LUNG CANCER
Improved Survival in Never-Smokers vs Current Smokers With Primary Adenocarcinoma of the Lung

https://doi.org/10.1378/chest.126.2.347Get rights and content

Study objectives:

Adenocarcinoma of the lung is now the most common histologic subtype of lung cancer in the United States. To determine if there are survival differences in never-smokers and current smokers with adenocarcinoma, we conducted an analysis of lung adenocarcinomas seen at the H. Lee Moffitt Cancer Center, and looked for demographic and survival differences in the two groups.

Design:

Data were gathered through the tumor registry at the H. Lee Moffitt Cancer Center and confirmed by chart review. A total of 132 documented never-smokers and 522 current smokers with lung adenocarcinoma were included. Detailed demographic survival information were gathered and tabulated. Former smokers were not included in the study. Multivariate analyses were performed using the Cox regression method to identify variables with independent prognostic significance. Life table actuarial analyses were performed to determine survival. Differences between survival curves were estimated using the log-rank test.

Results:

The mean age at diagnosis for never-smokers was higher as compared to current smokers: 63.5 years vs 59.4 years (p = 0.0005). In addition, there was an increased percentage of female subjects in the never-smoker category: 78% vs 54% (p < 0.0001). There was a statistically significant difference in survival between current smokers and never-smokers (p = 0.004). The Kaplan-Meier estimates at 5 years were 16% for current smokers and 23% for never-smokers. On multivariate analyses, smoking was identified as an independent negative prognostic factor.

Conclusion:

Our data show that never-smokers with adenocarcinoma are predominantly female, present at a higher mean age, and have improved survival when compared to current smokers. By multivariate analyses, the never-smoking status was found to be an independent predictor of improved survival. The survival difference may be partly influenced by less comorbidity among never-smokers. Nevertheless, owing to differences in the mechanism of carcinogenesis (in smokers vs nonsmokers), demographic factors, tumor behavior and survival, adenocarcinomas occurring in never-smokers may display a distinct natural history and may warrant further investigation as a separate entity with epidemiologic studies and clinical trials designed specifically for this category of non-small cell lung cancer.

Section snippets

Materials and Methods

Patients with lung cancer seeking treatment at the H. Lee Moffitt Cancer Center between 1985 and 2000 filled out a questionnaire developed by the thoracic oncology program, in which detailed smoking information was collected. Hence, demographic data including a detailed smoking history were prospectively collected. All patients who were histopathologically confirmed to have adenocarcinoma (or bronchioloalveolar carcinoma [BAC]) of pulmonary origin were included in this analysis. Survival data

Results

A total of 141 documented never-smokers with primary adenocarcinoma of the lung were registered between 1985 and 2000. Seven of the 141 patients were excluded from the study due to ambiguity of stage assigned at presentation, and 2 patients were excluded after chart review revealed a smoking history. There were 542 current smokers identified. Twenty of the 542 patients were excluded from the study secondary to ambiguity in staging assigned.

The demographic characteristics of both the cohorts are

Discussion

Multiple chemicals in cigarette smoke are presumed to induce carcinogenesis in smokers. However, no such insult exists in never-smokers, suggesting an alternate mechanism of carcinogenesis and therefore a distinct natural history and tumor biology. We performed this analysis to determine whether demographic characteristics and survival would be disparate in the never-smokers vs current smokers with lung adenocarcinoma.

Our studies indicate that never-smoking patients with lung adenocarcinoma

Conclusions

Our data show that never-smokers with adenocarcinoma are predominantly women, present at a higher age, and have improved survival when compared to current smokers. The survival difference may be partly influenced by less comorbidity among never-smokers. We conclude that owing to differences in mechanism of carcinogenesis, demographic factors, tumor behavior, and survival, adenocarcinomas occurring in never-smokers may warrant further investigation as a separate entity. A better understanding of

ACKNOWLEDGMENT

The authors thank Mr. K. G. Rajan for editorial assistance.

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