Osteoradionecrosis
Osteoradionecrosis, or ORN, is the most serious possible complication facing the oral cancer patient. A condition of the non vital bone in a site of radiotherapy (RT), Osteoradionecrosis is bone that has died as a complication of radiotherapy. Because radiation works to destroy cancerous cells through the deprivation of oxygen and vital nutrients, it inevitably destroys normal cells as well, damaging small arteries and reducing circulation to the area of the mandible. Not an infection itself, it is the bone’s reduced ability to heal and the resulting lesions, pain and fragility. Insufficient blood supply to the irradiated areas decreases the ability to heal, and any subsequent infections to the jaw can pose a huge risk to the patient. Though it is possible to develop spontaneously, ORN most frequently occurs when an insult to the bone is sustained in the irradiated area, such as related subsequent surgery or biopsy, tooth extractions or denture irritations.
Clinical manifestations and symptoms range from mild to severe and include:
- pain
- swelling
- reduced mobility of the jaw
- drainage
- exposed bone in the maxilla and/or mandible
- bone destruction
Symptoms vary depending on the location and the extent of damage to the bone. Many people do not experience any symptoms for month, or even years after the Radiation treatment.
The true frequency of ORN is difficult to determine though the incidence has greatly decreased in the last several years. Currently, the most representative study shows the incidence at 8% of patients developing the complication. Increased understanding of condition advances in radiotherapy and radiotherapy protocols along with a multidisciplinary approach and better patient education has played a large part in reducing the incidence.
There are many factors that can contribute to the development of ORN. Though any patient having received 40 gray (Gy) radiation administered to the mandible is at risk, it is more common in patients who have received more than 60 (Gy) radiation therapy. Since many oral cancer patients have as much as 70 Gy of radiation you can see why this is of importance to them. There is also an increased risk for those who receive a combination of both radiation and chemotherapy. The location and size of the primary tumor are other compounding factors. When the resulting lesion from a removed tumor is large and located on the floor of the mouth, the rate of incidence of ORN more than doubles. The immunologic and nutritional health of the patient at the time of treatment also seems to increase the risk as does smoking that the time of treatment.
Even with the newer protocols which more efficiently deliver radiation, preventative measures should be taken to help reduce the risk or severity of osteoradionecrosis. The maxilla and mandible, or upper and lower jaw, are unique in that they are the only bones directly in contact with external conditions through the gingival attachment of the teeth, which poses greater potential for disease and infection. Prior to treatment, a patient should have a full dental evaluation by a dentist trained in dealing with the concerns of oral cancer. Each tooth should be meticulously evaluated, charted and an individual treatment plan developed for each tooth. Any teeth that are unable to be restored are commonly extracted 2-3 weeks prior to treatment to allow sufficient time for healing. During treatment, a patient is likely to experience mucositis and xerostomia which can change the oral environment and tissue resilience which causes an increased risk of dental caries (cavities) and periodontal disease. The bacterial load of the mouth is greater than any other site of the body and consequently, any changes to that environment can be the conduit of infection. Local oral infections are common resulting from the growth of opportunities organisms, thriving in the compromised oral environment. Because of this, the mouth is more sensitive to injury and special care is to be taken which includes the use of prescribed mouthwash.
Since osteoradionecrosis is a non healing wound of the bone, its treatment can be difficult to manage. It is for this reason that ORN should be a concern before radiotherapy and any preventative measures taken. Most cases respond well, though slowly, to conservative treatments for both the control of pain and long-term oral antibiotic therapy. In cases that do not respond well to antibiotic therapy, local debridement, or the removal of the infected bone, is an option in more severe cases.
Hyperbaric Oxygen Therapy (HBO) has proven to be effective, though it has been slow to be accepted universally. More control studies are needed to confirm the effectiveness of HBO Therapy, however the proximity and scarcity of the expensive equipment make comprehensive results difficult to attain. There is, at least, general agreement that HBO treatments raise tissue oxygen levels which can affect the healing process and give greater infection control. Many studies show that HBO treatments are more effective than penicillin with patients showing a significantly lower rate of necrosis. One of the advantages to this treatment is that it is non-invasive and painless. Patients are placed in pressurized chambers while pure oxygen is compressed into the chamber. The treatments raise tissue oxygen levels and causes proliferation of blood vessels. (More information about hyperbaric oxygen treatments)
More advanced cases of ORN require radical surgery. A concern in the treatment of ORN is the possibility of local recurrence of a malignancy, which in many cases will not be identified until a pathologic examination of the removed bone has been completed. It is for this reason that some doctors believe that the surgical treatment of ORN should be treated with the same aggressiveness as the primary tumor surgery.
All patients with ORN should follow up with their physicians and dentists regularly, and follow prescribed treatment plans.