Effect of hyperbaric oxygen therapy on a murine squamous cell carcinoma model.

BACKGROUND Hyperbaric oxygen (HBO) therapy is sometimes used to assist in wound healing after major head and neck cancer surgery. However, there is concern that HBO treatments might enhance the growth of any residual microscopic disease. This was studied in a mouse model of squamous cell carcinoma (SCC). METHODS SCC-VII/SF tumor cells were cultured, and then injected (3 × 10(3) cells) into C3H/HeJ mice in 5 groups: subcutaneous (SQ) control (n = 13), SQ-immediate (n = 12), SQ-delayed (n = 13), tail vein control (n = 8), and tail vein immediate (n = 9). The 3 experimental groups were subjected to HBO therapy, 2.4 atm for 90 minutes, 5 days per week for 4 weeks, starting on postinjection day 3 ("immediate") or 10 ("delayed"). Tumors in the SQ mice were measured 3 times per week. Lung metastases in the tail vein mice were counted at necropsy. RESULTS At postimplantation day 28, when the immediate group completed its HBO therapy, the tumor volume in the SQ-immediate group was 49.1% higher than the control group, and the SQ-delayed group was 105.1% higher than controls (p < .05). Two weeks later, the SQ-immediate group and SQ-delayed group tumor volumes were still significantly higher than controls, but the difference was smaller (18.4% and 43.8%, respectively; p < .05 only for the delayed group). The tail vein groups had similar numbers of lung metastases, with a mean of 8.7 metastases in the control group and 9.0 metastases in the HBO group (not significant [NS]). CONCLUSION This study suggests that HBO therapy does accelerate the growth of microscopic foci of SCCs. This finding differs from some earlier studies and warrants further study.