Hyperbaric oxygen is still needed in the management and prevention of mandibular necrosis: a response to Mr. Richard Clarke

Mr. Richard Clarke presents in this Journal his arguments against continued application of hyperbaric oxygen (HBO2) therapy to the pre-extraction neoadjuvant treatment or the treatment of frank mandibular ORN. In the same article he advocates a promising renewed interest in HBO2 as a radiosensitizer. Arguments against HBO2 prior to extractions are based on several papers which consistently include low-risk patients. The just-released HOPON trial reports a negative pre-extraction outcome for HBO2, but patients were enrolled with radiation doses as low as 50Gy. For advanced mandibular necrosis (Marx Stage III) requiring resection, fibular free flap reconstruction is advocated. A high complication rate with free flaps is acknowledged but the magnitude of these complications is not discussed. A cost savings for this procedure is suggested, but no mention is made of the typical cost of the procedure ($90,000) or the requirement of a typical one-week hospital stay, including an initial one or two days in the ICU. Nor is mention made of the very low rate of subsequent dental rehabilitation. The success reported by Delainian, et al. employing pentoxifylline, Vitamin E and sometimes a bisphosphonate is equated to the four decades of HBO2 success with the Marx protocol for Stage I and II ORN. In the phase II trial by Delainian (not randomized) six of her 54 patients died secondary to sepsis, and she graded patients as complete responders if 5mm or less bone was exposed. Even at entry patients had an average of only 1.7 cm exposed bone and treatment was prolonged (16 + or -9 months). Any cost comparison studies will have to account for the indirect expenses of this prolonged treatment including lost productivity.

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.