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KAREN H.CALHOUNMDRONALD B.KUPPERSMITHMD
The subject of marginal mandibulectomy in surgical treatment of oral cancers has been debated in the literature over the past 40 years. Dr Wax and colleagues have presented a reasonable review of the subject and outlined the pros and cons of marginal vs segmental mandibulectomy, the rationale behind choosing the operative procedure, and the reported results in the literature. In the end, they conclude that a variety of preoperative assessments including clinical examination, radiological studies, examination under anesthesia, and intraoperative judgment should be exercised to choose the appropriate surgical procedure when the mandible is at risk of invasion by cancer.
Jatin P. Shah, MD, MS(Surg), FRACS
Historically, marginal mandibulectomy was considered for surgical excision of oral cancer to preserve form and function in those patients whose oral cancers either approached or superficially eroded the alveolar process of the mandible. As the nomenclature indicates, this procedure was designed to obtain margins around the primary tumor. Because appropriate reconstructive methods were not available, aggressive marginal mandibulectomies were performed even in previously irradiated patients to avoid the functional and aesthetic consequences of a segmental mandibulectomy. However, with the increasing application of microvascular free-tissue transfer and the excellent methods of mandible reconstruction available now, one should seriously consider avoiding aggressive marginal mandibulectomies or marginal mandibulectomies in irradiated mandibles, both of which put the residual mandible at risk of fracture.
Local recurrence rates following marginal and segmental mandibulectomy are comparable in the literature, but unfortunately the patient populations are not comparable because there is significant selection bias in choosing patients for these respective operative procedures. One would not perform a marginal mandibulectomy in patients with gross extension of tumor to the cancellous part of the mandible where segmental mandibulectomy is necessary and, by the same token, one would seldom perform a segmental mandibulectomy where there is no evidence from any of the preoperative evaluation methods described above of bone invasion. In such situations, a marginal mandibulectomy is considered appropriate to secure margins around the tumor. Thus, local tumor control should not be considered a parameter to demonstrate the superiority or comparative equality of the 2 procedures. Both procedures have a place in the surgical treatment of oral cancer in appropriately selected patients.
Nonetheless, contraindications to marginal mandibulectomy have been well defined: gross destruction of the cortical or cancellous part of the mandible demonstrated on preoperative radiological studies; invasion of the mandibular canal by cancer; massive soft tissue disease surrounding the lingual or the lateral cortex of the mandible; and presence of tumor on the alveolar process of an irradiated edentulous mandible. Relative contraindications for marginal mandibulectomy include the reduced vertical height of the bone in an edentulous mandible. With advancing age, the alveolar process atrophies, bringing the alveolar canal closer to the surface of the gum and thus reducing the vertical height of the body of the mandible. In such patients, not only is marginal mandibulectomy technically difficult because of the limited height of the bone, but injury to the endostial blood supply in the alveolar canal of the mandible puts the residual mandible after marginal mandibulectomy at risk of avascular necrosis and a pathological fracture.
In selected patients being considered for marginal mandibulectomy, in addition to the evaluation of the mandible by panoramic radiography and a CT scan, one may obtain a dentascan to study the cortex and the alveolar ridge of the mandible in detail at the site of concern. While negative dentascan findings do not rule out invasion of bone, the demonstration of cortical erosion would alert the surgeon to the potential invasion of bone and allow him or her to choose the appropriate surgical procedure. Rapid analysis of mandibular margins by frozen section techniques using smears from the resected portion of the cancellous part of the mandible is one technique that might add to the safety of a marginal mandibulectomy from an oncologic standpoint. However, one must appreciate that negative smears do not rule out the presence of tumor. If indeed such smear examination confirms the presence of tumor, the operation should be converted to a segmental mandibulectomy. Similarly, following completion of marginal mandibulectomy, if there is concern regarding the mechanical stability of the mandible at the site of marginal mandibulectomy, one may provide reinforcement at that site with application of a miniplate or a reconstruction plate to reinforce the integrity of the mandible. I must, however, disagree with the authors regarding the technique of stripping the periosteum from the mandible at the site of the tumor and then making a decision regarding marginal or segmental mandibulectomy. Such a maneuver violates the principle of monobloc resection of cancer and potentially increases the risk of local failure by "cutting through tumor."
In conclusion, marginal mandibulectomy is an oncologically sound surgical procedure for patients with oral cancer under select circumstances. Preoperative examination under anesthesia, appropriate radiological studies, and the exercise of sound surgical judgment all are required when selecting patients for marginal resection of the mandible. One should remember that it is not a "marginal" operation. It is indeed an adequate operation to secure margins around the primary tumor when the tumor is in the proximity of the mandible.
Shah JP. The Role of Marginal Mandibulectomy in the Surgical Management of Oral Cancer. Arch Otolaryngol Head Neck Surg. 2002;128(5):604–605. doi:10.1001/archotol.128.5.604
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