Physical activity at diagnosis is associated with tumor downstaging after neoadjuvant chemoradiotherapy in patients with rectal cancer

Background: Patients with rectal cancer are often treated with neoadjuvant chemoradiotherapy, followed by a waiting period and surgical resection. Good or complete response to neoadjuvant chemoradiotherapy might enable organ preservation, which highlights the need to increase response rates. Pre-clinical studies suggest that physical activity during neoadjuvant chemoradiotherapy may improve tumor downstaging. Purpose: To investigate whether physical activity and physical functioning of patients with rectal cancer at diagnosis are associated with tumor downstaging after neoadjuvant chemoradiotherapy. Materials and methods: Patients were included if they participated in the Dutch Prospective ColoRectal Cancer Cohort, a nationwide cohort providing an infrastructure for scientific research, and received neoadjuvant chemoradiotherapy for rectal cancer. Tumor downstaging was dichotomized into good/complete or moderate/poor downstaging. Physical activity (total physical activity, moderate-to-vigorous physical activity (MVPA), and Dutch physical activity guideline adherence) and physical functioning were assessed using questionnaires. Logistic regression analyses were performed to examine associations of physical activity and physical functioning with tumor downstaging, adjusted for relevant confounders. Results: 268 patients (aged 62 +/- 11 years, 33 % female) with rectal cancer were included. Patients with moderate (OR = 2.07; 95%CI = 1.07 - 4.07; p = 0.03) or high (OR = 2.05; 95%CI = 1.05 - 4.07; p = 0.04) levels of MVPA were more likely to have good/complete tumor downstaging than patients with low levels. No significant associations with tumor downstaging were found for total physical activity, Dutch physical activity guideline adherence, and physical functioning. Conclusions: We found augmented tumor downstaging in patients with rectal cancer with moderate or high levels of self-reported MVPA before the start of neoadjuvant chemoradiotherapy compared to patients with low levels.