Lung metastatic load limitation with hyperbaric oxygen.

Haroon TMY, Patel M, Al-Mehdi AB. Lung metastatic load limitation with hyperbaric oxygen. Undersea Hyperb Med 2007; 34(2): 83-90. Despite some theoretical concern about cancer-enhancing effects of hyperbaric oxygen (HBO 2 ) therapy, it is frequently administered to cancer patients. We evaluated the growth of murine breast cancer cells in the lung after hyperbaric oxygen treatment in an experimental metastasis assay. Young nu/nu mice were injected intravenously with 3 × 10 3 4T1-GFP tumor cells per g body weight followed by lung isolation, perfusion, and intact organ epifluorescence microscopy 1 to 37 days after injection. A group of animals (n=32) was exposed once daily for 5 days a week to 45 min of 2.8 ATA hyperbaric oxygen (HBO 2 ) in a research animal HBO 2 chamber. Control animals (n=31) were not subjected to HBO 2 treatment, but received similar intravenous administration of 3 × 10 3 4T1-GFP tumor cells. Single tumor cells and colonies were counted in the subpleural vessels in areas of about 0.5 cm 2 of lung surface. HBO 2 treatment did not lead to an increase in the number of the large or small colonies in the lungs. Rather, a significant reduction in the number of the large colonies was observed at 1 and 16 to 21-day periods of measurements after hyperbaric treatment. However, most importantly, there was a significant decrease in large colony size in the HBO 2 group during all periods of observation. The results indicate that HBO 2 is not prometastatic for breast cancer cells; rather it restricts the growth of large tumor cell colonies.