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O24 - Cancer Control and Epidemiology III (ID 134)
- Event: WCLC 2013
- Type: Oral Abstract Session
- Track: Prevention & Epidemiology
- Presentations: 1
O24.05 - The impact of body mass index on survival in stage 3 and 4 lung cancer (ID 663)
16:15 - 17:45 | Author(s): L. Coate
Obesity has been shown to be an adverse prognostic factor in several cancers, including breast, colorectal, endometrial, ovarian, pancreatic and prostate. However, studies of body mass index (BMI) and outcomes in lung cancer are lacking. Understanding the clinical impact of body weight on cancer outcomes is important given the high prevalence of obesity globally. We retrospectively evaluated the distribution of BMI at diagnosis and its effects on survival in stage 3 and 4 lung cancer patients.
1,121 patients with stage 3 or 4 lung cancer from a single institution were analyzed. Clinicopathologic data were collected retrospectively. Adjusted hazard ratios (aHR) for overall survival (OS) and progression-free survival (PFS) were generated by Cox regression for each BMI (kg/m) category (underweight: <18.5, normal: 18.5-24.9, overweight: 25.0-29.9, obese: ≥30), after adjusting for age, gender, Charlson Comorbidity Index, performance status (PS), clinical stage and treatment regimen.
In this cohort (n=1,121), the frequencies of stage 3A, 3B and 4 lung cancers were 35%, 32% and 33%, respectively. There were 633 (57%) adenocarcinomas, 238 (21%) squamous cell carcinomas, 38 (3%) small cell lung cancers, and 210 (19%) other histologies. Patients had variable BMI: 82 (7%) underweight, 550 (49%) normal weight, 333 (30%) overweight, 156 (14%) obese. Being overweight/obese was associated with older age (p=0.002) and stage 3A disease (p=0.001); underweight patients were more likely current smokers (p<0.001). OS was significantly decreased with age ≥65, males, PS 2-3, stage 4, and lack of systemic treatment (p<0.001). Median OS in underweight, normal weight, overweight and obese patients were 14, 23, 24 and 26 months, respectively. Compared with BMI ≥18.5, being underweight was associated with significantly poorer OS (aHR 1.33, 95% CI 1.01-1.77, p=0.045), but not PFS (aHR 1.12, 95% CI 0.86-1.46, p=0.414). The magnitude of this association was greatest among those aged less than 65 years (aHR 1.57, 95% CI 1.11-2.22, p=0.011).
In stage 3 and 4 lung cancer, being underweight at diagnosis is associated with significantly poorer OS, especially in patients younger than 65 years of age. Lower BMI is mostly observed in current smokers, while above normal BMI is seen in older patients and stage 3A disease. Unlike other malignancies, obesity does not increase mortality in this population. The BMI-survival relationship in lung cancer requires further study.
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