OBJECTIVE

The aim of this study was to evaluate the association of differential body water composition with survival in patients with lung cancer.

METHODS

This retrospective cohort study included 1314 patients diagnosed with lung cancer in 80 Chinese institutions from May 2013 to August 2020. We calculated hazard ratios (HRs) to evaluate the associations of all-cause mortality with extracellular water (ECW) and intracellular water (ICW). Cox proportional risk regression models were adjusted for sociodemographic characteristics, tumor characteristics, treatment, body mass index (BMI), and body composition measures. We also evaluated cross-classification of the dichotomy of ECW and ICW with outcomes. The association among ECW, ICW, and survival was evaluated via Cox regression and the restricted cubic-spline model using a two-sided P value.

RESULTS

The study included 819 (62%) men and 495 (28%) women. The HR of lung cancer mortality significantly decreased as ECW increased (HR, 0.96; 95% confidence interval [CI], 0.93-1.00) and ICW (HR, 0.97; 95% CI, 0.95-1.00) with cutoff values of 10.5 and 16.3 L, respectively. When patients were cross-classified into categories of sex, age, BMI, visceral fat index, pathology, tumor stage, tumor burden, total bilirubin, and neutrophil count, ICW and ECW were protective factors. Only sex interacted significantly with ICW or ECW. High ICW and ECW had significant protective effects, and women had a greater risk for death than men in the case of either poor ICW or poor ECW. Sensitivity analysis showed the protective effect of the higher dichotomy of ICW (HR, 0.52; 95% CI, 0.35-0.78) and ECW (HR, 0.45; 95% CI, 0.31-0.66) on female lung cancer patients by removing patients who died within 12 mo of diagnosis.

CONCLUSION

Greater ICW and ECW, especially ICW, were independent predictors for better survival in patients with lung cancer. Female patients were more vulnerable to dehydration than male patients.