Predictors of Physical and Functional Loss in Advanced-Stage Lung Cancer Patients Receiving Platinum Chemotherapy

Introduction: Muscle wasting has detrimental effects, including increased mortality. Identifying patients at risk can guide treatment efforts.

Methods: POWER 1 and 2 were randomized, double-blind, placebo-controlled, multinational phase III trials that studied 600 patients with lung cancer at the start of chemotherapy; the studies' aim was to assess the efficacy of enobosarm on prevention and treatment of muscle loss. We performed a secondary analysis restricted to the control group, using a cumulative logit model for ordinal outcome to determine which baseline characteristics predicted physical and functional loss during chemotherapy.

Results: In all, 53% of patients had loss of lean body mass and 49% had loss of stair climb power (SCP) at day 84 of treatment. Of the 322 patients who received placebo, 232 with observable outcome and baseline covariates were included for lean body mass analysis and 236 for SCP analysis. More advanced disease predicted a higher probability of greater physical loss (OR = 1.96; 95% confidence interval [CI]: 1.14-3.36). Three factors predicted higher probability of SCP loss: taxane chemotherapy (OR = 1.73; 95% CI: 1.06-2.83), tobacco use before chemotherapy (OR = 2.15, 95% CI: 1.10-4.18), and SCP at baseline (OR = 1.01, 95% CI: 1.004-1.015). Higher body mass index was a protective factor for functional loss (OR = 0.85; 95% CI: 0.73-0.98). A higher Eastern Cooperative Oncology Group Performance Status trended toward being predictive of greater probability of both physical loss (0.767) and functional loss (0.070), but the results were not statistically significant.

Conclusions: Approximately 50% of patients with advanced lung cancer who were undergoing chemotherapy had ongoing loss of muscle mass and muscle function. Advanced stage predicted physical loss. Tobacco use and taxane chemotherapy predicted functional loss. Body mass index was a protective factor for functional loss. We identified predictors of physical and functional loss that could be used as therapeutic targets or to guide treatment efforts.