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Higher BMI associated with differential survival in NSCLC
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Among patients with advanced non–small cell lung cancer, those who were obese exhibited superior outcomes early on compared with normal-weight and overweight patients, according to study results.
However, the mortality risk for obese patients from any cause increased dramatically after 16 months.
Previous trials have established an inverse association between BMI and risk for fatal lung cancers, yet studies designed to evaluate the link between BMI and outcomes for patients with lung cancer have been limited.
In the current study, Suzanne E. Dahlberg, PhD, a research scientist in the department of biostatistics and computational biology at Dana-Farber Cancer Institute, and colleagues assessed the association of BMI and outcomes in 2,585 eligible patients enrolled in three consecutive first-line systemic chemotherapy trials conducted by the ECOG from 1993 to 2004.
Researchers classified patients as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5 to <25 kg/m2), overweight (BMI 25 to <30 kg/m2) and obese (BMI ≥30 kg/m2).
The researchers analyzed OS and PFS, as well as reasons for treatment discontinuation.
Consistent with the general population, 4.6% of patients were underweight, 44.1% were normal weight, 34.3% of patients were classified as overweight and 16.9% were obese.
Median OS varied considerably based on patients’ weight, with obese patients experiencing superior survival outcomes early on compared with normal-weight and overweight patients (HR=0.86; 95% CI, 0.75-0.99).
However, obese patients began to experience increased hazard once they had been on the study for more than 16 months (HR=1.54; 95% CI, 1.22-1.94), researchers wrote.
“This indicates that the protective effect of obesity in lung cancer patients is for a limited time, after which the ultimate impact of obesity on survival from all causes supersedes,” the researchers wrote. “Our results are consistent with observational studies demonstrating an inverse association between BMI and risk of fatal lung cancers, as well as with outcomes for patients with lymphoma and renal cancer.”
Disclosure:The researchers report no relevant financial disclosures.
Perspective
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Matthew Gubens, MD, MS
As an ever-growing segment of our population, obese patients warrant particular attention and study given significant potential differences in drug metabolism and even cancer biology. This article won't change practice, and the lack of information about smoking status and about weight changes following study discontinuation are limitations. However, it provides rigorously collected prospective data that can help us develop testable hypotheses about the so-called "obesity paradox" — whereby patients with higher BMI enjoy better survival, at least initially — and about the interaction of comorbidities like diabetes and its treatments (metformin, in particular, which may well have anti-cancer effect) and tobacco use with cancer outcomes.
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