Cancers of the Upper Aerodigestive Tract: Cervical Exenteration




Introduction



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Rarely, locally extensive but nonmetastatic cancers of the upper aerodigestive tract require resection. Cancers of the larynx, cervical trachea, hypopharynx, cervical esophagus, and thyroid can be exenterated with a pharyngo-laryngo-tracheo-esophagectomy as primary therapy, salvage after failed primary therapy, treatment of locally recurrent cancer, treatment of benign complications of successful primary therapy, or long-term palliation. The enormity of these procedures is further overshadowed by the likely possibility of limited survival, the potential for significant complications, and the expected negative impact upon quality of life. However, in curatively resected and properly reconstructed patients, long-lasting effects are little more than that experienced by the laryngectomy patient.




Preoperative Evaluation and Preparation



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Clinical staging is mandatory to determine the eligibility for exenteration.1 Distant metastatic cancer (cM1 or ycM1) is excluded by PET/CT and cancer-specific imaging (e.g., thyroid scanning for differentiated thyroid cancers). Regional nodal metastases (cN1 or ycN1) are frequently detected by physical examination and confirmed by cytologic evaluation of fine-needle aspiration (FNA) specimens. However, cervical ultrasonography and FNA may be necessary to better examine and determine regional nodal classification. Local extent of the primary cancer (cT or ycT) is critical in deciding resectability, but is frequently underestimated by preoperative investigations. Regardless, local invasion should be evaluated with particular with respect to particular carotid artery, vertebral body, and mediastinal involvement. This may require multiple imaging modalities (angiography, MRI, fine-cut CT, barium esophagram, bone scan, etc.). The proximal and distal extent of the cancer is assessed by oropharyngoscopy, bronchoscopy, and esophagoscopy (panendoscopy). These endoscopic procedures are accompanied by the appropriate biopsies of the primary cancer and its margins. The skin and subcutaneous tissue overlying and in the vicinity of the primary cancer must be examined to exclude malignant invasion or severe radiation damage if previously administered.



The reconstruction must be planned and prospective organs of replacement/reconstruction evaluated. Vascular insufficiency secondary to smoking accelerated atherosclerosis may necessitate angiographic assessment of these organs and tissues. Gastroscopy and colonoscopy are essential to exclude intrinsic disease if the stomach or colon is being contemplated for replacement. The tissue planned for pedicle or free flaps must be assessed and alternatives considered and evaluated. A mediastinal tracheostomy may be necessary for reconstruction if there is significant length of tracheal involvement. This may require division of the innominate artery to avoid postoperative arterial erosion and ensuing hemorrhagic complications. Therefore, angiographic assessment of cerebral blood supply and patency of the Circle of Willis is compulsory if mediastinal tracheostomy and innominate artery division are planned.



As in all patients undergoing airway and esophageal surgery, cardiopulmonary assessment is essential. Comorbidities must be evaluated and the affected organ systems optimized preoperatively. During this time, the nutritional status and fitness of the patient is maximized.




The Operation



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Preparation and Positioning


The patient is positioned supine. Arterial line, oxygen saturation probe, and venous catheter placements are guided by the possibility of division of the innominate artery and sacrifice of the left innominate vein. Similarly EKG pad placement may be affected by resection of the primary cancer or harvesting of reconstructive flaps. EEG leads may be placed for monitoring if there is concern of compromising cerebral perfusion. Techniques and equipment necessary for endotracheal intubation will be determined by the primary cancer and presence of an established tracheostomy. Provisions must be made for cross-table ventilation during surgery.



The operative field is prepared and draped from patient’s chin to suprapubic abdomen and bilaterally to midaxillary lines. The thigh and forearm/arm may be included in the field if they will be used for flap harvesting or skin grafting.



Exploration


The operation starts with a collar incision placed above the sternal notch. The incision should be positioned to permit extension laterally, if necessary, over the clavicles and inferior over the manubrium (Fig. 66-1). If a tracheostomy exists, the stoma should be included in the incision. Invaded or radiation-damaged skin is excluded from the flaps, excised, and left attached to the cancer. The superior subcutaneous flap is raised above the hyoid bone, and the inferior flap is lifted to the sternal notch. Cranial, caudal, lateral, and deep invasion are assessed during this mobilization. If uninvolved the strap muscles are then separated in the midline or if invaded they are divided and left attached to the primary cancer. Lateral dissection determines if the carotid sheath is involved by the cancer. The prevertebral space is developed to assure the resection can be completed posteriorly. These steps confirm cancer resectability and to this point no irreversible steps have been taken.




Figure 66-1


A collar incision is made above the sternal notch with inclusion of the tracheostomy stoma if one exists.





Resection


Typically, the resection begins inferiorly. If a mediastinal tracheostomy is necessary, the incision is extended in the midline inferiorly over the manubrium. The lateral myocutaneous flaps are raised off the bony chest wall, and the manubrium is excised along with the first and second cartilages and the clavicular heads (breast-plate). The level of tracheal division is selected. The trachea is circumferentially mobilized at this site and lateral dissection restricted below this point. Lateral traction sutures are placed in the tracheal wall one cartilage below the anticipated position of tracheal transection (Fig. 66-2). This will stabilize the trachea and facilitate tracheal intubation during cross-field ventilation. Once the trachea has been divided and distal intubation obtained, the tracheal margin is sent for frozen-section analysis. Some thyroid and airway (adenoid cystic carcinoma) cancers may not involve or minimally invade the esophagus, permitting esophageal preservation without compromising the resection. In patients requiring cervical exenteration the point of esophageal transection is determined. The extent of the primary cancer and the method and organ of esophageal reconstruction will dictate this level. If free flap is being used for reconstruction, the esophagus is divided in the low neck and this margin is sent for frozen-section analysis.




Figure 66-2


The tumor is exposed by raising the superior subcutaneous flap above the hyoid bone and lifting the inferior flap up to the sternal notch. The tumor is inspected for invasion both superiorly and inferiorly. Lateral dissection determines if the carotid sheath is involved by the tumor. The trachea is mobilized circumferentially. Lateral traction sutures are placed in the tracheal wall one cartilage below the anticipated position of tracheal transection.


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Dec 30, 2018 | Posted by in VASCULAR SURGERY | Comments Off on Cancers of the Upper Aerodigestive Tract: Cervical Exenteration
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