Contemporary management of the oral cancer is primarily focused on preservation of the continuity of the mandible, because it serves several important roles in function, esthetic and psychological aspects of the face.
The desired result is achieved either by preserving continuity or by reconstruction of the arch, if it is necessary to sacrifice a segment of the bone for oncologic clearance. Of these two alternatives, preservation of the arch has the advantage of simplicity, and therefore would be preferable if it is compatible with effective tumor excision i.e. oncologically safe.
The ideal cancer operation for oral cancers, the so-called composite resection, was introduced by Crile in 1906, based on the concept of the lymphatic drainage of the buccal mucosa as described by Polya and von Navratil in 1902. In their anatomic studies they conceptualized that lymphatics from the buccal mucosa passed to the neck nodes through lymphatic channels in the mandibular periosteum.
This laid the foundation of the radical surgery which removed the cervical lymph node-bearing regions (neck dissection) and intervening lymphatic channels (mandibulectomy) in continuity with the oral primary, irrespective whether the mandible was infiltrated by the cancer or not.
However, these extensive surgeries were marred by very high perioperative mortality and significant functional morbidity without enhancing the cure rates. Remarkable developments in anesthesia, instrumentation, antibiotics and perioperative nutrition management made these advanced surgical techniques possible and thus the advent of the modern composite operation (Figure 1 and 2).
Modlin and Johnson (1955) stressed on the sacrifice of a portion of the mandible even when the mandible was not involved, they emphasized that the segment of mandible should be removed without hesitation and without considering function or esthetic aspects.
The remarkable studies by Marchetta and Sako (1966), Marchetta et al (1971) and Carter et al (1983) demonstrated that periosteal invasion does not occur without actual tumor-bone abutment. They determined that infiltration of the mandible occurred by direct invasion rather than by lymphatic spread. These landmark publications laid the foundation of the mandibular preservation surgeries without compromising local tumor control. These studies were supplemented by histologic studies by O’Brien et al (1986) and McGregor and MacDonald (1987-1989).
As a result of these studies, a variety of conservative mandibulectomy techniques are being increasingly used now a day. Marginal mandibulectomy is now an accepted technique for mandibular preservation without compromise of the oncologic safety. It is indicated for the lesions abutting or early invasion of the mandible i.e less than 5mm (Figure 3 and 4).
Not only should adequate bone height be preserves but care should be taken not to injure vascular supply of inferior neurovascular bundle. This will prevent avascular necrosis and iatrogenic fractures. In case radiotherapy is also given in such a situation, there is very high likely hood of developing osteoradionecrosis (Figure 5).
Care should be taken to make the ends curved and smooth with minimal separation of the bone from the periosteum.Height of mandible preserved should not be less than 10 mm (figure 6).If a situation arises where the mandibular height preserved is less than 10mm, one should not hesitate in either doing prophylactic mini plate fixation or converting it into a proper segmental mandibulaectomy.
It should always be kept in mind that it is better to perform good segmental mandibulectomy rather than an ill performed marginal mandibulecty. Despite recent advances in reconstruction techniques, the functional and cosmetic ramifications are still significant, so more conservative surgical extirpation in respect to mandibular preservation can have significant functional and cosmetic implication for the oral cancer patients. However, failure to remove the mandible when carcinoma has invaded it allows progression of disease. Determination of the extent of mandibular invasion by oral cancer is crucial for treatment planning.
Treatment failures of oral squamous cell carcinoma usually results from local recurrence. Clinical examination and radiographic studies to determine the extent of mandibular resection required are not usually precise. If it is difficult to predict extent of mandibular involvement, the oncologic surgeon needs an intraoperative assessment for predicting adequate resection.
Dr. Arsheed Hakeem is a senior consultant at the department of head and neck Oncology, Apollo cancer hospitals. Hyderabad. India. He is a member of the seasoned team of specialists that made Apollo hospital the most preferred by patients all across the globe. He can be reached via Apollo hospital website.