Exercise and Sedentary Behavior Do Not Alter Lung or Liver Metastases in a Murine Colon Cancer Model

Epidemiological studies indicate that physical activity reduces cancer risk and mortality, while sedentary behavior exerts opposite effects. However, their impact on tumor metastasis remains unclear. This study investigated the effects of physical exercise and sedentary behavior on lung and liver metastatic growth in a murine colon carcinoma model.

Male BALB/c mice were randomized into three groups: exercise (voluntary wheel running), sedentary (restricted cage size, no climbing), and control (standard housing conditions). After 4 wk, lung or liver metastases were induced by injecting C26 colon carcinoma cells into the tail vein or portal vein, respectively. In the primary experiments, mice continued their assigned activity protocols for 20 additional d before sacrifice. In a separate lung metastasis survival study, mice were euthanized upon reaching predefined humane endpoints. In-cage locomotor activity was continuously monitored using Digital Ventilated Cages. Metastatic growth was assessed via lung and liver weight measurements and in vivo bioluminescence imaging.

During 7 wk of voluntary exercise, mice ran a median of 4.5 km/d (interquartile range 3.8-5.3) in the lung metastasis model and 6.6 km/d (interquartile range 5.6-7.6) in the liver metastasis model. Sedentary mice showed a reduction of over 30% in average daily walking distance within their home cage compared to the exercise and control groups in both metastasis models (P < 0.0001). However, metastatic growth in the lungs and liver was not significantly affected by physical exercise or sedentary behavior. Similarly, these activity protocols did not alter survival of mice with lung metastases.

Real-time monitoring via the Digital Ventilated Cage system confirmed differences in locomotor activity among groups. However, neither exercise nor sedentary behavior significantly affected lung or liver metastatic growth, nor did they impact survival.