The effect of hyperbaric oxygen therapy on tumour growth in a mouse model of colorectal cancer liver metastases

Background and aims: Hyperbaric oxygen (HBO) therapy involves the administration of 100% oxygen at high pressure. It has been used to treat a variety of conditions including non-healing wounds, carbon monoxide poisoning, and as an adjuvant to radiotherapy or chemotherapy. The effect of HBO alone on the growth of malignancy remains controversial. This study investigates the impact of HBO on tumour growth, kinetics and microcirculation of colorectal cancer liver metastases in an experimental model. Methods: Male CBA mice were induced with colorectal liver metastases via an intrasplenic injection of a murine derived colorectal cell line. Tumours were examined using quantitative stereological analysis, histology and scanning electron microscopy of microvascular resin casts. The effect of HBO on tumour proliferation and apoptosis was quantified using immunohistochemistry. Results: Daily exposure to HBO at 2.4 atm for 90 min had no effect on the volume of liver metastases. At day 13, HBO caused a significant reduction in tumour necrosis and proliferation compared to the non-HBO group (p = 0.002 and p = 0.008, respectively). By day 25 however, no differences were observed (p > 0.05). No differences in apoptosis or microvascular architecture were observed. Conclusion: HBO did not have a tumour stimulatory effect on colorectal liver metastases and may potentially be used safely in conjunction with other therapeutic treatment modalities. (c) 2006 Elsevier Ltd. All rights reserved.