Mayo Clinic ENT pioneers have found a new method to reform the mandible (lower jaw) of oral cancer patients .
Senior investigator of the study, Eric Moore, M.D., said that without reconstructive procedures difficulties such as in eating, speaking and facial abnormalities would be seen in mandible-removed oral cancer patients.
'We think this new process can be a huge advantage for patients and a good tool for reconstructive surgeons,' says Daniel Price, M.D., Mayo Clinic ear, nose and throat surgery resident and lead study investigator. 'We're excited about it. It will not completely replace the current mandible reconstruction method -- transfer of bone -- but down the road, I think that this method of reconstruction will be done regularly in patients with cancer involving the mandible.'
Patients who might be candidates for the new reconstructive and treatment procedure have oral cancer involving part of the mandible. To completely remove the tumor surgically, surgeons have to remove part of the mandible. Without reconstructive surgery, patients would have difficulty eating and speaking, and would develop a significant facial deformity, says Eric Moore, M.D., Mayo Clinic ear, nose and throat surgeon and senior study investigator.
The new method, which the investigators tested in rabbits, used distraction osteogenesis after tumor removal surgery to restore the missing portion of a patient's jaw. With distraction osteogenesis, the surgeon made a cut at one of the remaining ends of the patient's jawbone. As the break healed, the first phase of growth, soft tissue, appeared. The surgeon then stretched the pliable soft tissue under the tension of a device to fill in the gap in the patient's jaw. Within 24 hours of completing the stretching process, physicians started administering radiation therapy to the mandible to decrease the likelihood of cancer recurrence. As the soft tissue healed, it hardened into bone. The investigators found that the radiation therapy, which they had suspected could interrupt the bone consolidation prior to the study, had no ill effects on the bone's healing.
'Patients with large oral tumors should have radiation therapy after surgery to decrease the chances of cancer recurrence,' says Dr. Price. 'Radiation needs to be completed 13 to 14 weeks after the patient's cancer diagnosis to achieve maximum effect. As these patients require mandible reconstruction after tumor removal, we wanted to find a way to get both the radiation and the reconstruction done quickly and concurrently.'
Dr. Price says that it is also preferable to start the reconstruction when the tumor is removed, as demonstrated in this method, rather than wait until radiation therapy is completed, because immediate reconstruction minimizes scar tissue and is better tolerated by the patient.
The standard procedure for jaw reconstruction following removal of an oral cancer is transfer of bone from the patient's fibula in the leg, along with surrounding muscle, skin and the supplying vessels. Although the aesthetic and functional result for the mandible can be good, this procedure has drawbacks, including:
The surgery takes all day to complete and is expensive
The patient has a second surgical site to heal (leg and mandible) and is less mobile post-surgery
In male patients, the transfer of fibula and surrounding skin can lead to the appearance of leg hair inside the patient's mouth
The surgery is not feasible for patients who do not have healthy vessels in their legs.
The aesthetic result in the leg post-surgery is less than ideal.
The surgery can inadvertently damage the leg's nerves, leaving the patient with some leg weakness
The fibula bone can die following transfer
'If we could avoid the whole process of going to another part of the body in order to reconstruct a patient's jaw, it would be best,' says Dr. Moore.
Drs. Price and Moore had been performing similar distraction osteogenesis in children born with small jawbones and wondered about the feasibility of using the procedure for adult oral cancer patients. Thus, they embarked on this research project to test it in animals and have tried this method on human oral cancer patients who were not appropriate candidates for the fibula transfer surgery. They have also utilized the method in patients who have benign tumors or who have suffered a trauma.
The patients who have had distraction osteogenesis performed by Drs. Price and Moore compared the level of discomfort to having orthodontic braces. The devices used for the stretching procedure are submerged and not visible.
The next step in this research, according to Dr. Price, is to study the distraction osteogenesis plus radiation therapy method in larger animals, comparing them to animals who are given distraction osteogenesis without radiation therapy.