Abstract 857: A preliminary study of the correlation of tumor size and epidemiological characteristics in patients with non-small cell lung cancer
Authors: Chen Xing , Merriman Kelly W. , Gorlov Ivan P. , Weng Shih-Feng , Foy Millennia , Keener Gwendolyn , Spitz Margaret R. , Kimmel Marek , Gorlova Olga Y. 
Published: February 2011

Introduction: Tumor size at diagnosis is an indicator for prognosis and the type of treatment of lung cancer. It reflects tumor growth rate and predicts metastasis status and survival in patients. It is therefore of great importance to evaluate what factors are associated with tumor size at diagnosis.

Experimental procedures: We reviewed the electronic medical records of 1190 lung cancer patients from M.D. Anderson Cancer Center to collect information on tumor characteristics (lung cancer radiologically or surgically assessed tumor size) and patient characteristics (including age, gender, ethnicity, smoking history and vital status at the last contact date). We used t-test, Kruskal-Wallis test and linear regression to explore the relationship between the tumor size at diagnosis and a number of epidemiological factors derived from questionnaire data.

Results: Smoking status was associated with tumor size at the time of diagnosis. We observed that never smokers presented with significantly smaller tumors (2.83 cm) than smokers, whether former smokers (3.50cm; P=0.001), recent quitters (4.00cm; P&lt;0.001) or current smokers (3.55cm; P=0.004). There was no significant difference (global P=0.061 from Kruskal-Wallis test) by tumor size in the three smoker groups. No significant difference was observed between younger (age≤65; 3.70 cm) and older (age&gt;65; 3.30 cm; P=0.071) patients. Men had larger tumors (4.00 cm) than women (3.00 cm; P&lt;0.001) at presentation. The gender-stratified analysis did not show evidence (P&gt;0.05) of relationship between either height or body mass index (BMI) and tumor size. Patients reporting dust or asbestos exposure presented with larger tumors while exposure to X-ray examination showed an opposite result. Hormone replacement therapy use in women was not associated with lung tumor size. Patients self-reporting with emphysema had smaller tumors (3.00 cm) at presentation than those without emphysema (3.70 cm; P=0.001). There was a difference in tumor size by cell type (adenocarcinoma, 3.42 cm vs squamous cell carcinoma, 4.52 cm, P&lt;0.01) and degree of differentiation (not differentiated to poorly, 4.33 cm vs moderately to well, 3.50 cm, P&lt;0.01). African Americans (4.10 cm) had significantly larger tumors (P&lt;0.001) at diagnosis compared to Caucasian patients (3.50 cm), although the sample size for African Americans was limited to 127. Health care system utilization patterns did not explain the observed associations.

Conclusions: In this study, lung tumor size at presentation was significantly associated with gender, ethnicity, smoking status, emphysema, cell type, degree of differentiation, X-ray examinations, and exposures to dust and asbestos. Mathematical modeling that allows for different growth and metastatic rate of tumors may help further understand the impact of various factors on the natural history of lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 857.