Osteoradionecrosis—A review of current concepts in defining the extent of the disease and a new classification proposal

Refining the definition of mandibular osteoradionecrosis in clinical trials: The cancer research UK HOPON trial (Hyperbaric Oxygen for the Prevention of Osteoradionecrosis)

INTRODUCTION

Mandibular osteoradionecrosis (ORN) is a common and serious complication of head and neck radiotherapy for which there is little reliable evidence for prevention or treatment. The diagnosis and classification of ORN have been inconsistently and imprecisely defined, even in clinical trials.

METHODS

A systematic review of diagnosis and classifications of ORN with specific focus on clinical trials is presented. The most suitable classification was evaluated for consistency using blinded independent review of outcome data (clinical photographs and radiographs) in the HOPON trial.

RESULTS

Of 16 ORN classifications found, only one (Notani) appeared suitable as an endpoint in clinical trials. Clinical records of 217 timepoints were analysed amongst 94 randomised patients in the HOPON trial. The only inconsistency in classification arose where minor bone spicules (MBS) were apparent, which occurred in 19% of patients. Some trial investigators judged MBS as clinically unimportant and not reflecting ORN, others classified as ORN based on rigid definitions in common clinical use. When MBS was added as a distinct category to the Notani classification this ambiguity was resolved and agreement between observers was achieved.

DISCUSSION

Most definitions and clinical classifications are based on retrospective case series and may be unsuitable for prospective interventional trials of ORN prevention or treatment. When ORN is used as a primary or secondary outcome in prospective clinical trials, the use of Notani classification with the additional category of MBS is recommended as it avoids subjectivity and enhances reliability and consistency of reporting.

Pentoxifylline - a review of its use in osteoradionecrosis

Pentoxifylline has been used to treat complications related to fibrosis for over 20 years. Formerly used to treat those after radiotherapy such as osteoradionecrosis (ORN), it is now being tried for medication-related osteonecrosis of the jaw (MRONJ), which can occur after prolonged use of bisphosphonates. We review theories on the formation of fibrosis in patients with ORN, discuss the pharmacology of pentoxifylline and vitamin E, and report published outcomes. To our knowledge no prospective randomised controlled trial has investigated the benefits of these agents in cases of ORN, but reported outcomes in many published case series are encouraging.

The Osteosarcoradionecrosis as an Unfavorable Result Following Head and Neck Tumor Ablation and Microsurgical Reconstruction

Osteoradionecrosis is preferably called osteosarcoradionecrosis to adequately cover the scope of the problem: multitissue necrosis. The changes following radiotherapy and leading to necrosis are further classified into 2 phases based on improved understanding of the underlying mechanisms. The reversible-damage phase could respond to the medical treatment, while the irreversible damage phase or osteosarcoradionecrosis may benefit from complete resection and free flap reconstruction. The role of ablation and reconstruction in paving the road for the development of osteosarcoradionecrosis is discussed, a case study provided, and a refined reconstructive approach proposed.

Osteoradionecrosis and intensity modulated radiation therapy: An overview

Osteoradionecrosis (ORN) is an ongoing topic, especially about its definition, pathogenesis, staging system and management algorithm. But what about its real incidence in intensity modulated radiotherapy (IMRT) era? This paper discusses the mandible in radiation therapy planning as organ at risk and reviews the literature for evidence of radiation damage, discussing likely dose constraints and the use of IMRT to reduce radiation dose to this structure. PubMed search was performed.

Osteoradionecrosis and medication-related osteonecrosis of the jaw: similarities and differences

The purpose of this study was to compare medication-related osteonecrosis of the jaw (MRONJ) with osteoradionecrosis (ORN). Group 1 comprised 74 MRONJ patients (93 lesions) and group 2 comprised 59 ORN patients (69 lesions). Patient characteristics, clinical presentation of the lesions, the presence of complications, and the relationship with previous dental extractions were analyzed for both groups. Significant differences were found between the groups with regard to the characteristics of the patient populations, extraction as the precipitating event, the type of initial complaint, the prevalence of pain, and the location of the lesions. In the ORN group, significantly more patients complained of pain (P=0.0108) compared with the MRONJ group. Furthermore, significantly more pathological fractures (P<0.0001) and skin fistulae (P<0.0001) occurred in the ORN group. The treatment was more often conservative in the MRONJ group than in the ORN group (61.3% vs. 36.2%). Despite similarities in terms of imaging, risk factors, prevention, and treatment, MRONJ and ORN are two distinct pathological entities, as highlighted by the differences in patient characteristics, the initial clinical presentation, course of the disease, and outcome.

Hyperbaric oxygen therapy and osteonecrosis

Osteonecrosis of the jaw may be caused by radiation, medication, or infection. Optimal therapy requires a multimodal approach that combines surgery with adjuvant treatments. This review focuses on the use of adjunctive hyperbaric oxygen therapy for this condition. In addition to evidence regarding the basic and clinical science behind hyperbaric oxygen therapy, controversies in the field and economic implications are discussed.

Use of the Integra skin regeneration system in an intraoral mandibular defect in osteoradionecrosis

The objective was to trial the use of the Integra skin regeneration system intraorally to promote healing of an intraoral defect in osteoradionecrosis (ORN), thereby avoiding the necessity for mucosal flaps, free flaps, or skin grafts. A 54-year-old male patient presented with a pathological mandibular fracture at the angle, related to previous radiotherapy for tonsillar carcinoma, after the development of ORN. The fracture site was debrided and fixed with a reconstruction plate and the intraoral defect was dressed with the Integra two-layer system and an overlying pack. Three weeks later, the pack and silicone layer of the regeneration system were removed, showing early granulation over the previously exposed bone. At 8 weeks postoperative, the defect had healed completely with no need for further reconstruction. Using the method described, excellent healing was seen with the Integra skin regeneration system. A new use for the Integra skin regeneration system has been identified in the authors' unit. This method is minimally invasive and resulted in good healing in the case presented. The need for further reconstruction with associated increased patient morbidity was avoided in this case.

Jaw osteoradionecrosis and dental extraction after head and neck radiotherapy: A nationwide population-based retrospective study in Taiwan

OBJECTIVES

Osteoradionecrosis of the jaws (ORNJ) is painful for patients and relatively difficult to treat clinically. The high risk of ORNJ for post radiotherapy R/T dental extraction is known; however, many patients still have to have teeth extracted after head and neck R/T. The objective of the present study is to review post R/T dental extraction and determine the ORNJ risk.

MATERIALS AND METHODS

We preformed a retrospective cohort study of 1759 patients with head and neck cancer s/p R/T from a random sample of 1,000,000 insurants in the National Health Insurance Research Database during 2000-2013 in Taiwan. Statistical methods included two-proportion Z-test.

RESULTS

We evaluated two cohorts: 522 patients with post R/T dental extraction and 1237 patients without post R/T extraction. Overall moderate-to-severe ORNJ after R/T was 2.22% (39/1759), and a total of 39 ORNJ cases were noted during an average of 3.02years (range: 0.62-8.89years, ±2.07). ORNJ prevalence in the overall post R/T extraction-exposed cohort (5.17%, 27/522) was significantly greater than that in the unexposed cohort (0.97%, 12/1237). In a group of patients with ⩽5 post R/T dental extractions (n=373), the ORNJ risk was 2.4% (ORNJ case n=9); in a group of patients with >5 dental extractions (n=149), the ORNJ risk was 12.1% (ORNJ case n=18) (Z-score=4.5062; p-value<0.0001). In the extraction-exposed cohort, the ORNJ risk is higher if the index day to first extraction day was ⩽0.5year (n=103) compared with the group with the index day to first extraction day >0.5year (n=419) (Z-score=-2.1506; p-value=0.0315).

CONCLUSION

A tooth extraction time less than half a year after R/T or during the head and neck R/T period, and extraction tooth number ⩽5 would significant lower the ORNJ prevalence.

Prevention of radiation-induced bone pathology through combined pharmacologic cytoprotection and angiogenic stimulation

Pathologic fractures and associated non-unions arising in previously irradiated bone are severely debilitating diseases. Although radiation is known to have deleterious effects on healthy tissue cellularity and vascularity, no clinically accepted pharmacologic interventions currently exist to target these destructive mechanisms within osseous tissues. We utilized amifostine-a cellular radioprotectant-and deferoxamine-an angiogenic stimulant-to simultaneously target the cellular and vascular niches within irradiated bone in a rat model of mandibular fracture repair following irradiation. Rats treated with combined therapy were compared to those undergoing treatment with singular amifostine or deferoxamine therapy, nontreated/irradiated animals (XFx) and non-treated/non-irradiated animals (Fx). 3D angiographic modeling, histology, Bone Mineral Density Distribution and mechanical metrics were utilized to assess therapeutic efficacy. We observed diminished metrics for all outcomes when comparing XFx to Fx alone, indicating the damaging effects of radiation. Across all outcomes, only the combined treatment group improved upon XFx levels, normalized all metrics to Fx levels, and was consistently as good as, or superior to the other treatment options (p<0.05). Collectively, our data demonstrate that pharmacologically targeting the cellular and vascular environments within irradiated bone prevents bone injury and enhances fracture healing.

Osteoradionecrosis of the Jaws: Clinico-Therapeutic Management: A Literature Review and Update

Osteoradionecrosis is one of the most serious oral complications of head and neck cancer treatment. It is a severe delayed radiation-induced injury, characterized by bone tissue necrosis and failure to heal for at least 3 months. In most cases osteoradionecrosis gradually progresses, becoming more extensive and painful that leads to infection and pathological fracture. The present paper provides a literature review and update on the risk factors underlying osteoradionecrosis, its clinical and diagnostic particulars, prevention and most widely accepted treatment options including the latest treatment modalities. Lastly, a new early management protocol is proposed based on the current clinical criteria relating to osteonecrosis secondary to treatment with bisphosphonates, together with the adoption of new therapies supported by increased levels of evidence.

Development of mandibular osteoradionecrosis in rats: Importance of dental extraction

OBJECTIVES

To develop an animal model of mandibular osteoradionecrosis (ORN) using a high-energy radiation source (as used in human therapeutics) and to assess the role of tooth extraction on ORN development.

MATERIALS AND METHODS (STUDY DESIGN)

Ten animals were irradiated with a single 35- or 50-Gy dose. Three weeks later, the second left mandibular molar was extracted from three animals in each group. Nine weeks after irradiation, the animals were euthanized, with an injection of contrast agent in the bloodstream to highlight vascularization. Mandibles were harvested and studied using micro-CT, histology, tartrate-resistant acid phosphatase activity and scanning electron microscopy.

RESULTS

This study demonstrates that a single 50-Gy dose associated with molar extraction is necessary for ORN development. In these conditions, absence of healing of the mucosa and bone, dental effects, fibrosis, an increase in osteoclast activity and a decrease in vascularization were observed. We also determined that molar extraction increases the impact of the cellular effects of radiation.

CONCLUSION

The mandibular ORN animal model was validated after 50-Gy irradiation and molar extraction. The results of this study therefore support an animal ORN model and tissue engineering strategies will now be developed to regenerate bone for patients with head and neck cancer.

Osteoradionecrosis of the hyoid bone--a novel application of the Sonopet ultrasonic aspirator

A 66-year-old man with a history of squamous cell carcinoma of the right tonsil presented to the emergency department with two life-threatening episodes of haemoptysis 9 months after completion of chemoradiation. He was evaluated to rule out recurrent malignancy, and was determined to have osteoradionecrosis of his hyoid bone that had led to an oropharyngeal fistula. Given the proximity to branches of the external carotid, he was offered tracheostomy and resection of the protruding necrotic bone with ultrasonic bone aspirator, which was placed down the shaft of the laryngoscope to minimise damage to adjacent structures. He tolerated the procedure well with complete resolution of exposed bone on follow-up laryngoscopy.