Abstract B143: Association between smoking status and disease stage at presentation: Analysis of a prospective NSCLC cohort
Authors: Singh Navneet , Aggarwal Ashutosh N. , Behera Digambar , Jindal Surinder K. 
Published: May 2012

Background: Smoking remains the most important risk factor for development of lung cancer (LC). There is paucity of data on its influence on LC stage at the time of diagnosis. The current study was conducted to assess the association between smoking status and disease stage among LC patients presenting to a tertiary care institute in North India.

Methods: Prospectively collected data on 340 newly diagnosed LC patients over a 20 month period after January 01, 2008 was analyzed. Demographic and histological characteristics and details of smoking status (n=336) were noted. Smoking index (SI), as previously published by us (Jindal SK, et al. Thorax 1982; 37: 343–7), was defined as the number of bidis/cigarettes smoked per day multiplied by the number of years smoked. Patients were categorized into three groups based on SI: non-smokers and light [SI≤100] smokers (Group I; n=120), moderate [SI=101–300] smokers (Group II; n=74) and heavy [SI≥301] smokers (Group III; n=142). Numerical and categorical data were compared between groups using one way analysis of variance (ANOVA) and chi-square test respectively. Multivariable logistic regression analysis was performed to derive adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

Results: The ratio of bidi:cigarette smokers was 4.88:1. Significant differences were observed among groups I, II and III in relation to mean (standard deviation) age [55.1 (12.9), 57.9 (9.5) and 61.3 (9.8) years respectively; p&lt; 0.001] and gender distribution [number of males being 71 (59.2%), 68 (91.9%) and 139 (97.9%) respectively; p&lt;0.001]. Overall baseline Karnofsky performance status was 100, 90, 80 and ≤70 in 57.4%, 27.4%, 7.6% and 7.6% of patients respectively and did not differ significantly among the three groups. Distribution of histological types in groups I, II and III respectively was: squamous cell (32.5%, 32.4% and 43.7%), adenocarcinoma (36.7%, 18.9% and 16.9%), large cell (1.7%, 5.4% and 2.8%), undifferentiated non-small cell LC (NSCLC) (10.8%, 16.2% and 14.8%), small cell (SCLC) (12.5%, 25.7% and 21.1%) and miscellaneous (5.8%, 1.4% and 0.7%). The group differences were statistically significant (p=0.001). Among NSCLC patients, statistically differing (p=0.008) stage distribution was seen among groups I, II and III respectively: Stages I–II (1.0%, 11.1% and 3.6%), stage IIIA (5.1%, 16.7% and 16.2%), stage IIIB (39.8%, 37.0% and 43.2%) and stage IV (54.1%, 35.2% and 37.0%). For SCLC, groups I, II and III had limited disease in 60.0%, 42.1% and 46.7% patients respectively and extensive disease in 40.0%, 57.9% and 53.3% patients respectively; p=0.564. On multivariable logistic regression analysis, the following factors (after adjustment for gender and age) were found to be independently associated with early stage (I–IIIA) presentation of NSCLC: SI=101–300 [OR=4.01 (95% CI=1.29–12.49)] and undifferentiated NSCLC histology [OR= 0.14 (95% CI=0.03–0.65)].

Conclusions: Among newly diagnosed LC patients in North India, significant differences exist between non/light smokers, moderate smokers and heavy smokers in relation to age, gender, histological distribution and stage of NSCLC at presentation. Along with histology, SI is an independent predictor for presentation of NSCLC in early stage. Further studies are needed to ascertain reasons for the observed association and its implications for disease prevention.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B143.