Among over 7,000 patients with cancer, higher baseline fatigue before systemic therapy was linked to an increased risk of severe, life-threatening, and fatal adverse events.

Question Is baseline patient-reported fatigue associated with subsequent cancer treatment−related adverse events?

Findings In this cohort study and pooled analysis of 7,086 patients from 17 SWOG phase 2 and 3 randomized clinical trials, patients who reported baseline fatigue had a significantly higher risk of severe, life-threatening, and fatal adverse events. In addition, a dose-response pattern was observed, with patients reporting high fatigue vs no fatigue having a nearly 5-fold increased risk of fatal toxic effects.

Meaning Patient fatigue reported before cancer treatment may serve as an early clinical marker of risk for toxic effects and could help guide personalized treatment strategies.