Premorbid body mass index and mortality in patients with lung cancer: A systematic review and meta-analysis

- Elevated premorbid BMI was associated with reduced lung cancer mortality.
- Overweight and obese individuals respectively had 16% and 19% reduced mortality, compared to individuals with normal BMI.
- These findings were observed across sexes, smoking status, geographic region, study type, method of ascertaining BMI and study type.

ObjectivesWe aimed to assess the association between premorbid obesity, measured using body mass index (BMI) and lung cancer-related mortality, through a systematic review and meta-analysis.Materials and MethodsObservational studies reporting statistical measures of association between premorbid BMI categories and lung cancer-related mortality were included in our study. We estimated hazard ratios (aHR) with 95% confidence intervals (CI), comparing lung cancer-related mortality across BMI categories. The main outcome measure was lung cancer-related mortality in obese (BMI ≥ 30 kg/m2) and overweight participants (BMI 25.0-29.9 kg/m2), compared with normal BMI participants.ResultsWe included 14 studies (including 2 pooled cohort studies) comprising 3,008,137 cancer-free participants at inception, reporting 28,592 lung cancer-related deaths. On meta-analysis, we observed a significantly lower lung cancer-related mortality in overweight (aHR, 0.76; 95% CI, 0.68-0.85) and obese (aHR, 0.68, 95% CI; 0.57-0.81) participants as compared to participants with normal BMI, with considerable heterogeneity; after excluding one study with large effect size, a more conservative and consistent association was observed between BMI and lung cancer-related mortality (overweight vs. normal BMI: aHR, 0.84; 95% CI, 0.79-0.90; obese vs. normal BMI: aHR, 0.81; 95% CI, 0.75-0.87), with moderate heterogeneity. Were similar in men vs. women, non-smokers vs. smokers, and Western vs Asia-Pacific populations.ConclusionsBased on meta-analysis, we observed an independent protective association between premorbid obesity and lung cancer-related mortality. This association was observed across sex, smoking status and geographic region. Further studies are needed to prospectively study this association.