Abstract
BACKGROUND: One in three patients with stage III colon cancer will experience tumor recurrence. It is uncertain whether physical activity during and after postoperative chemotherapy for stage III colon cancer improves overall survival after tumor recurrence. METHODS: A prospective cohort study nested within a randomized multicenter trial of patients initially diagnosed with stage III colon cancer who experienced tumor recurrence (N = 399) was conducted. Postoperative physical activity before tumor recurrence was measured. Physical activity energy expenditure was quantified via metabolic equivalent task hours per week (MET-h/week). The primary end point was overall survival after tumor recurrence. Multivariable flexible parametric survival models estimated relative and absolute effects with two-sided hypothesis tests. RESULTS: Compared with patients expending <3.0 MET-h/week of physical activity (comparable to <1.0 h/week of brisk walking), patients with ≥18.0 MET-h/week of physical activity (comparable to 6 h/week of brisk walking) had a 33% relative improvement in overall survival time after tumor recurrence (hazard ratio, 0.67; 95% CI, 0.42-0.96). The overall survival rate at 3 years after tumor recurrence was 61.3% (95% CI, 51.8%-69.2%) with <3.0 MET-h/week of physical activity and 72.2% (95% CI, 63.1%-79.6%) with ≥18 MET-h/week of physical activity (risk difference, 10.9 percentage points; 95% CI, 1.2-20.8 percentage points). CONCLUSIONS: Higher postoperative physical activity is associated with improved overall survival after tumor recurrence in patients initially diagnosed with stage III colon cancer. These data may be relevant to patients who, despite optimal postoperative medical therapy, have a high risk of tumor recurrence.