Transoral Laser Microsurgery in Carcinomas of the Oral Cavity, Pharynx, and Larynx

Jochen A. Werner, MD, Anja A. Dünne, MD, Benedikt J. Folz, MD, Burkard M. Lippert, MD

Disclosures

Cancer Control. 2002;9(5) 

In This Article

Oral Carcinomas

The surgical approach and histologic confirmation of clear margins for early stages of oral cancer differ slightly from those for other regions within the upper aerodigestive tract. The areas involved by tumor are exposed with the aid of gags and tongue depressors. Special instruments can be used to optimize the access to the operative site. For instance, small carcinomas (1 or 1.5 cm in diameter) of the tongue are excised en bloc but with a relatively wide resection margin of 5 to 10 mm. When excising the tumor, care must be taken to maintain a uniform tumor margin in the deeper muscular layers. If the superficial extension of the tumor is greater than 10 mm in diameter or if there are signs of deep infiltration, one or more incisions can be made through the tumor, depending on its localization and extent (Fig 1). Transecting the tumor may help to estimate more accurately the depth of tumor infiltration. These surgical steps are performed under the operation microscope and are designed to render a higher level of oncologic safety in the excision of these carcinomas.[4,5]

Figure 1.

(A) T2 carcinoma of the right margin of the mobile tongue before laser microsurgery. (B) Good functional results are seen 24 months following laser microsurgery.

Mobile Tongue and Floor of the Mouth

During laser microsurgical dissection, the tumor is traced into the surrounding healthy tissue regardless of the direction and degree of its extension. For carcinomas of the floor of the mouth, two conditions deserve a more detailed discussion (Fig 2). The first is the inclusion of excretory ducts of the sublingual and submandibular glands into the resection; the second is the modification of the procedure if the mandible is involved. The excretory ducts of the lesser salivary glands can be severed or partially resected. We rarely observe complications such as chronic inflammation with intermittent swelling of the gland, which may eventually necessitate the excision of the gland following laser microsurgical resection of oral carcinomas. This observation is explained by the fact that the main excretory duct is generally preserved in cases of superficial carcinomas. On the other hand, the pressure of the saliva is usually strong enough to keep the lumen open and prevent stenosis.

Figure 2.

(A) T1 carcinoma of the floor of the mouth before microsurgery and (B) 16 months after laser microsurgery.

At our institute, we excise the tumor with a safety margin of at least 5 mm. The periosteum can be dissected with the laser or a rasp. The basal surface is marked with blue ink and is submitted for histologic examination. If infiltration into the mandible is suspected, the area in question is widely excised. In resections of the floor of the mouth and the inferior surface of the mobile tongue, we cover the resected area with split thickness skin grafts that are usually harvested from the groin. The size of the graft should be larger than the size of the laser wound to compensate for expected shrinkage of the graft. Before we applied this technique regularly, we occasionally observed considerable scarring and subsequent reduction of tongue mobility.

Buccal Mucosa and Oral Surface of the Soft Palate

Superficial and exophytic carcinomas of the buccal mucosa that do not break through the skin of the cheek or infiltrate the parotid gland can be resected completely with the CO2 laser using a microsurgical technique. Laser microsurgical resection of small carcinomas of the buccal mucosa does not require coverage of the defect with grafts because these wounds usually heal spontaneously and without significant functional impairment.

Resection of carcinomas of the soft palate follows a similar pattern (Fig 3). The carcinomas are often larger than expected, which may lead to extensive defects of the soft palate with accompanying functional defects, including rhinophonia, which must be addressed. In palliative cases or in cases in which extensive surgical resections are not indicated, a palatal obturator can be utilized, or covering the defect with a flap might be considered. In these cases, reconstruction is best performed with the help of a free radial forearm flap.

Figure 3.

(A) T3 verrucous carcinoma of the soft and hard palate in an 85-year-old woman before laser microsurgery and (B) 20 months after laser microsurgery.

In these cases, CO2 laser surgery is well suited for the precise and hemostatic resection of carcinomas. The resulting defects, however, should be treated according to the same principles that are applied following conventional surgery.[6,7] Depending on the site and extent of the primary tumor, the resulting defect can be covered using reconstructive flap surgery. In cases of relevant defects of the soft palate, we prefer reconstruction with the free radial forearm flap. The reconstruction is often key in preventing velar insufficiency and thus regurgitation of ingested food into the nasopharynx or the nose. Laterally based oropharyngeal tumors may require excision via partial resection of the mandible. In these cases, we cover the defect with the greater pectoralis muscle.

Posterior Wall of the Oropharynx

Most small tumors of the posterior pharyngeal wall can be completely resected without any difficulties. If tumor extension has occurred toward the hypopharynx or nasopharynx is present, the resection is extended accordingly. The superior border usually can be exposed adequately with the help of palatal retractors. The bivalved laryngoscope is used in cases with significant inferior extension. Tumors with deep infiltration of the posterior wall of the oropharynx are managed similarly to those of the hypopharynx. However, this technique has limitations. For example, laser surgical resection does not appear to be indicated if the carcinoma infiltrates the anterior longitudinal ligament of the spine. Therefore,preoperative imaging studies such as magnetic resonance imaging are mandatory in these cases. If tumor extension into the nasopharynx is evident, transitory division of the soft palate is sometimes required to achieve an adequate exposure.

Lateral Wall of the Oropharynx

The surgical and histologic procedures for carcinomas of the tonsil differ slightly from those of other regions. The different tissue structure and growth characteristics of tumors in this area necessitate a modification of the surgical approach and histologic confirmation of a complete resection. Well-circumscribed lesions that are up to 1 cm in diameter and have a more superficial growth pattern can be excised en bloc. We also utilize en bloc resection for a larger tonsillar carcinoma located on the surface of the tonsil that still can be luxated. In these cases, transoral tumor tonsillectomy is performed (Fig 4). Larger tumors in the area of the tonsil are resected in several pieces as described by Steiner and Ambrosch.[8] We perform at least three horizontal incisions -- one superiorly, one through the middle, and one inferiorly. It is important to be aware of the depth of tumor extension during surgical procedures in the tonsillar area. Branches of the ascending palatine artery (from the facial artery) and the descending palatine artery (from the maxillary artery), as well as branches of the ascending pharyngeal artery, are ligated conventionally or with vascular clips.

Figure 4.

(A) Small T2 carcinoma of the left tonsil before transoral laser microsurgery and (B) 22 months following surgery.

The glossotonsillar sulcus is another high-risk area for deeper and more extensive resections involving larger arterial vessels such as the lingual artery and the external carotid artery. Other important structures in the immediate proximity are the hypoglossal and glossopharyngeal nerves. The same safety precautions apply here as in the area lateral to the tonsil. In these cases, we cover the defect with collagen mesh and fibrin glue. Patients with advanced oropharyngeal carcinomas are treated with neoadjuvant radiochemotherapy. Six to 8 weeks after radiochemotherapy, the tumor area is resected laser-surgically within the initial tumor border, and a unilateral or bilateral neck dissection is performed. To resect the tumor area properly, the tumor border is tattooed initially during panendoscopy. In our experience with a limited number of patients, laser surgical resection does not appear to be associated with delayed wound healing or an increase in the number of complications with regard to the functional outcome. Our results suggest that further investigation involving a larger number of patients is warranted.

Base of Tongue and Vallecula

A number of factors complicate the technically simple laser resection of carcinomas of the tongue. The relatively common tumor extensions, especially into the submucosal space, are oncologically unfavorable characteristics of these cancers. Identification of the tumor borders is more difficult in the tongue than in the larynx. The more pronounced carbonization encountered during laser surgery of tongue tissue is a result of the increased vascularization and the glandular tissue present in the tongue.

Laser surgical treatment of cancer of the base of the tongue presents a challenge even for experienced surgeons. Apart from the postcricoid region, the base of the tongue is the area of highest risk for endoscopic surgery, especially if exposure through the bivalved laryngoscope is not optimal. Also, differentiating between tumor and healthy tissue can be particularly difficult in the area of the tongue base due to obstruction by the lingual tonsil. In addition, achieving adequate access to this region to allow sufficient exposure to all areas involved by tumor can be difficult. In many cases, the surgeon can see only a particular segment and may lack any surrounding landmarks for orientation, such as the pyriform sinus or larynx.

Laser surgical removal of the lingual tonsil may be of oncologic relevance in the diagnostic workup of cancer of unknown primary (CUP syndrome). An occult primary tumor would more likely be revealed if the surgical specimen were processed during pathohistologic examination in serial sections rather than through random biopsies. In laser surgical resection of the lingual tonsil, care should be taken to avoid dissection into the lateral pharyngeal tissue or muscular layer, which may increase the risk of severe hemorrhage.

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