Abstract
Introduction
Approximately 1 of 4 patients with osteoradionecrosis (ORN) of the mandible develop ongoing disease despite extensive mandible resection to margins determined by the presence of bleeding bone at the time of surgery.
Objective
To determine whether pathologic examination of bony margins in assessing for the presence of necrotic edges is correlated with ongoing ORN.
Methods
Resected mandible specimens from 34 patients with severe mandibular ORN were examined histologically for the presence of necrotic margins and compared with clinical outcome of ORN persistence at follow-up.
Results
Median follow-up was 17.4 months. Eight specimens had histologic evidence of necrotic, nonviable bone at the margins of resections; however, there was no progression of disease among patients in this group. Twenty-six specimens were clear of necrotic margins; however, 8 patients from this group developed persistent disease.
Conclusions
Irradiated mandible is susceptible to ORN progression even if clinical and final histopathologic assessments confirm complete resection of necrotic bone margins. Progression of disease in ORN is not related to inadequate resection of necrotic bone.
1
Introduction
Osteoradionecrosis (ORN) of the mandible is characterized by irreversible bone loss associated with exposure to radiation therapy for the treatment of the head and neck cancer. Although the definition and pathogenesis still remain unclear, ORN of the mandible is clinically described as exposed irradiated bone that fails to heal over a period of 3 months . The incidence of ORN varies from 3% to 6% when the mandible is in the treatment volume and patients with irradiated mandibles exposed to cumulative doses greater than 60 Gy appear to be at highest risk . Osteoradionecrosis has been a significant and difficult clinical problem since radiation therapy became established in the 1950s for the treatment of oral and oropharyngeal malignancies. Even today, management of ORN remains controversial.
The current approach to early and limited ORN has been focused on oral hygiene improvement, local wound irrigation, debridement, curettage, and sequestrectomy oftentimes with a combination of long-term systemic antibiotics and hyperbaric oxygen therapy . This treatment plan is based on the view of ORN as a complication of hypoxic-hypocellular-hypovascular tissue. However, this conservative approach is ineffective in controlling extensive bone and soft tissue necrosis. Indeed, cases of advanced ORN with pathologic fractures, large amounts of necrotic tissue, or orocutaneous fistulas are unlikely to respond to conservative treatments. In these patients with extensive ORN of the mandible, radical resection of the mandible followed by microvascular composite flap reconstruction has emerged as the most reliable treatment option .
However, a recent report by our group showed that approximately 25% of patients with ORN of the mandible develop ongoing disease despite extensive mandible resection. The extent of resection in these surgeries is determined by excising necrotic bone until a bleeding edge is encountered. However, because ORN does progress in some patients despite this approach, we questioned whether ongoing disease in this population was related to inadequate resection of necrotic bone. We aimed to assess whether residual necrosis on final histopathologic analysis of specimen margins was correlated with ongoing ORN.
2
Methods
This study was approved by the University of California, Los Angeles Institutional Review Board. Forty patients with ORN of the jaw who underwent radical resection of the mandible followed by microvascular composite flap reconstruction between 1995 and 2009 were identified from a previously published data set . All patients had either failed to respond to conservative management, which included hyperbaric oxygen (HBO), long-term antibiotics, debridement, or had a pathologic fracture of the mandible at the time of their presentation. All patients were taken to surgery for radical resection of the affected mandible; the extent of resection was determined by resection of necrotic bone until a bleeding edge was encountered. No frozen sections of margins were requested. We reviewed the final permanent section of mandible specimen histopathology to assess the bony margins for the presence of necrotic edges. Six subjects were excluded because the slides containing the bony margins could not be found. Specimens with any involvement of bony margin necrosis were classified as “necrotic edge: yes.” Specimens with all margins clear of necrosis were classified as “necrotic edge: no” (see Figs. 1 and 2 ). The pathologists who reviewed the slides (coauthors BP and CL) were blinded to the actual results of whether the patients had experienced recurrence. Specimen margins were examined and results documented for 34 of 40 subjects.
We then reviewed clinic notes from the 34 patients to assess for clinical resolution vs progression of ORN at follow-up. Clinical resolution of ORN was defined as complete restoration of mucosal and cutaneous bone coverage and bony continuity, without clinical evidence of infection. Analysis for this study included calculation of sensitivity and specificity of specimen margin necrosis as a test for ORN progression.
2
Methods
This study was approved by the University of California, Los Angeles Institutional Review Board. Forty patients with ORN of the jaw who underwent radical resection of the mandible followed by microvascular composite flap reconstruction between 1995 and 2009 were identified from a previously published data set . All patients had either failed to respond to conservative management, which included hyperbaric oxygen (HBO), long-term antibiotics, debridement, or had a pathologic fracture of the mandible at the time of their presentation. All patients were taken to surgery for radical resection of the affected mandible; the extent of resection was determined by resection of necrotic bone until a bleeding edge was encountered. No frozen sections of margins were requested. We reviewed the final permanent section of mandible specimen histopathology to assess the bony margins for the presence of necrotic edges. Six subjects were excluded because the slides containing the bony margins could not be found. Specimens with any involvement of bony margin necrosis were classified as “necrotic edge: yes.” Specimens with all margins clear of necrosis were classified as “necrotic edge: no” (see Figs. 1 and 2 ). The pathologists who reviewed the slides (coauthors BP and CL) were blinded to the actual results of whether the patients had experienced recurrence. Specimen margins were examined and results documented for 34 of 40 subjects.
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