Challenges threaten, opportunity awaits hyperbaric medicine and the head and neck cancer patient
Over the past four decades, hyperbaric oxygen (HBO2) therapy has played a prominent role in both the prevention and treatment of mandibular osteoradionecrosis (ORN). It has done so on the strength of laboratory observations and clinical reports, yet only limited efficacy data. This dual role has come under increasing scrutiny in the modern radiotherapy (RT) and surgical eras. The ability to spare healthy “non-target” tissue has markedly improved since the two-dimensional planning and delivery techniques in use when HBO2’s prophylactic value was first demonstrated. A recent study failed to identify this same benefit in patients who received high-precision imaging and conformal RT. HBO2 therapy is under challenge as preferred treatment for early stage ORN. A recently introduced “fibroatrophic” mechanism contrasts with the hypovascular-hypocellular-hypoxic injury pattern that formed the basis for HBO2’s therapeutic use. This alternative pathophysiologic state appears to benefit from an oral antioxidant medication regimen. The continuing necessity of HBO2 in support of mandibular reconstruction for advanced ORN is in question. Microsurgery-based vascularized bone flaps increasingly represent standard care, invariably in the absence of perioperative HBO2. Renewed interest in hyperbaric oxygen as a radiation sensitizer offers some promise. Hypoxia remains a critical radio-resistant factor in many solid tumors. Malignant gliomas have been a primary focus of several small studies, with resulting improvements in local control and median survival. Hyperbaric radiation sensitization has recently addressed oropharyngeal cancer. Preliminary data indicates that addition of HBO2 to chemo-radiation standard of care is technically feasible, well tolerated and safe. A Phase II efficacy trial will investigate the potential for of HBO2 to improve progression-free and relapse-free survival in newly diagnosed locally advanced head and neck cancers. What follows is a review and summary of relevant peer-reviewed literature.