Resection of Cancer of the Tongue Base and Tonsil via the Transhyoid Approach†
Presented at the 102nd Annual Meeting of the American Laryngological, Rhinological and Otological Society, Inc., Palm Desert, California, April 27, 1999.
Objective To assess whether transhyoid resection of the tongue base and tonsil lesions is an effective approach to tumors involving this region compared with more traditional anterior surgical approaches that arbitrarily involve either segmental resection or division of the mandible.
Study Design Retrospective review.
Methods Since 1988, we have used a combined transhyoid and transoral approach to resect lesions involving the tongue base, tonsil, or both. Forty-one patients were identified who underwent surgical resection of lesions involving this region via this combined approach during this period. A stage-matched group of 41 patients was also identified in which patients underwent resection via traditional composite or mandibulotomy approaches and was used as a basis for comparison. Factors assessed included status of surgical margins, postoperative complications, degree of postoperative dysphagia, and long-term outcome.
Results Comparison between the two groups revealed similar rates of negative surgical margins. Levels of postoperative dysphagia, notably severe primarily in patients with either T4 or recurrent disease, were also similar between groups. Complication rates, especially with regard to fistula occurrence and mandible-healing problems, were significantly lower in the transhyoid group. Analysis of long-term outcome revealed similar patterns with regard to disease status in both groups.
Conclusions The combined transhyoid and transoral approach is an effective surgical option for a number of lesions affecting the tongue base, tonsil, or both. Although similar to other approaches with regard to postoperative function and disease outcome, the transhyoid approach is associated with decreased postoperative morbidity. However, tumors that e-tend to involve the mandible or pterygoid musculature or skull base are probably best suited for traditional approaches that involve division of the mandible.
Surgical approaches to tumors involving the base of the tongue, tonsil, or both often involve arbitrary composite resection of the mandible or, more recently, division of the mandible via a lip-splitting or visor flap approach followed by restoration of arch continuity by internal fixation techniques. Despite the wide surgical access afforded to lesions of the tongue base and tonsil by these anterior approaches, disadvantages of such approaches include subsequent alterations of speech and deglutition, malocclusion, wound healing problems, cosmetic deformity, and temporomandibular joint pain. 1–3
Although the suprahyoid approach to the pharynx has been classically described during the initial approach to lesions involving the supraglottic larynx, 4 its potential utility in providing access to other sites within the pharynx has been historically recognized. 5,6 Despite a number of early descriptions, however, its use by surgeons for much of the 20th century for carcinoma of the oropharynx has been limited, because of oncological concerns relating to inadequate exposure, awkward orientation, and violation of the pre-epiglottic space. 2,7,8
Within the past decade, however, a number of reports have been published describing similar approaches (transhyoid, suprahyoid, transpharyngeal) for small groups of patients with limited lesions of the tongue base, 9,10 as well as for more extensive lesions involving the tongue base, tonsillar fossa, or both, 11,12 with acceptable oncological and functional results. In 1994 we also reported our own favorable experience with 19 patients who underwent surgical resection of advanced lesions of the tongue base, tonsil, or both via a combined transhyoid and transoral approach. 13 Since then, we have continued to use the transhyoid approach for such lesions and, as a result, our experience with this approach has expanded significantly.
PATIENTS AND METHODS
A retrospective chart review of patients with a diagnosis of squamous cell carcinoma of the tongue base, tonsil, or both who were treated at the University of Illinois Eye and Ear Infirmary and West Side Veterans Administration (Chicago, IL) from 1977 to 1996 was conducted. Fifty-two patients were identified who underwent surgical resection of their tumors by means of (initially) a transhyoid-type approach. Of these patients, 11 required eventual mandibular division or segmental resection, because of tumor extent (i.e., pterygoid or mandibular involvement) or need for additional exposure. Thus 41 patients were identified who underwent resection solely via a transhyoid and transoral approach (transhyoid group). A stage-matched group of 41 patients—matched as closely as possible by TNM status as well as oropharyngeal subsite involvement (i.e., base of tongue vs. tonsil)—was also identified in whom surgery was carried out via composite resection or mandibulotomy approaches (mandibulotomy group) and analyzed as a basis for comparison (Table I). Relative proportions of patients for each stage undergoing adjuvant radiotherapy as part of their treatment, as well as radiation dose given, are shown in Table II. Factors assessed in both groups included status of surgical margins, postoperative complications (fistulae, wound infection, osteoradionecrosis), levels of postoperative dysphagia, and long-term disease outcome.
Table Table 1.. Tumor Characteristics (n = 82).
Table Table 2.. Postoperative Radiotherapy.
RT = radiotherapy.
A summary of our operative approach for transhyoid resection is as follows. After neck dissection as appropriate, the suprahyoid musculature is dissected off the hyoid bone and the stylomandibular ligament is released. The hyoid bone is resected in its entirety, avoiding injury to the contralateral lingual artery and hypoglossal nerve. In our experience, this maneuver allows for greater ease of closure by allowing tongue base rotation. Initial pharyngotomy is performed, guided both by prior endoscopy and by simultaneous transoral palpation of the tumor with an adequate margin away from the tumor. After widening the pharyngotomy, the tongue base can be grasped and everted into the wound. Additional inferior and medial tumor cuts are made. A large Richardson retractor is used to retract the tongue base and mandible anteriorly if necessary to expose the tonsillar fossa. After separation of the carotid sheath from the pharynx, additional cuts extending superiorly are accomplished. Final anterior and superior cuts are performed transorally, and the specimen is subsequently removed, after which frozen-section control of margins is typically carried out. As a result of extensive mobilization of the tongue base, primary closure is often easily performed, although flap reconstruction is occasionally required. Reapproximation of the divided strap musculature resuspends the larynx and accomplishes a second layer of closure.
Of the 41 patients who underwent transhyoid resection of their tumors, 9 had close (<1 mm) or positive margins on pathological examination, despite negative findings on examination of intraoperative frozen sections. Of the 41 patients in the mandibulotomy group, 11 had close or positive margins. However, the rate of positive margins between the two groups was not significantly different (Table III).
Table Table 3.. Outcome measures.
NA = not available; NS = not significant.
Of the 41 patients in the transhyoid group, 3 patients (7%) required recruitment of additional tissue by means of a regional myocutaneous flap for closure (Table III). In contrast, a myocutaneous flap was used in 13 of the 41 patients (31%) from the mandibulotomy group. This difference was found to be significant (P < .05). Postoperative complications with respect to fistula formation, wound infection, and the occurrence of osteoradionecrosis or osteomyelitis are outlined in Table III for both the transhyoid group and the mandibulotomy group. There were two instances of fistula in the transhyoid group (5%) compared with 10 in the mandibulotomy group (24%). Active wound infection (fever, cellulitis, increased leukocyte count) occurred in three patients in the transhyoid group (7%) compared with five patients in the mandibulotomy group (12%). Osteoradionecrosis of the mandible developed in only one patient from the transhyoid group (2%); in the mandibulotomy group, osteoradionecrosis or osteomyelitis developed in seven patients (17%). With respect to the incidences of fistula formation and mandible healing problems, those in the transhyoid group were found to be significantly lower than the corresponding incidences in the mandibulotomy group (P < .05).
Levels of postoperative dysphagia were correlated according to the need for continued enteral nutritional support via a feeding tube (Table III). Of evaluable patients, 24 patients in the transhyoid group (62%) and 21 patients in the mandibulotomy group (55%) required supplemental enteral support via a feeding tube for less than 3 months. An additional 8 patients in the transhyoid group (21%), as well as 10 patients in the mandibulotomy group (26%), required prolonged support beyond 3 months but were eventually able to obtain substantial nutritional intake via the oral route. Seven patients in the transhyoid group (18%) and eight patients in the mandibulotomy group (21%) experienced severe dysphagia and remained largely dependent on tube feeding for adequate nutrition. Most cases of severe dysphagia for both groups (6 of 7 in the transhyoid group, 8 of 8 in the mandibulotomy group) occurred in patients with extensive disease (T4) at the primary site or recurrent or persistent disease after previous radiotherapy. Comparisons of overall levels of dysphagia were found to be similar between the transhyoid and mandibulotomy groups. Long-term outcome results are shown in Table IV. As shown, survival between the transhyoid and mandibulotomy groups was similar with overall 5-year survivals of 47% and 45% for the transhyoid group and mandibulotomy groups, respectively.
Table Table 4.. Long-Term 5-Year Outcome (Cases Prior to 5/95).
NA = not available; NS = not significant.
Based on the initial favorable experience with the transhyoid approach, 13 we have continued to use this approach for most tongue base and tonsil lesions recommended for surgical resection at this institution. We acknowledge the limitations imposed on such an analysis by its retrospective nature, which introduces bias when attempting to make comparisons between groups (transhyoid vs. mandibulotomy). Although it was impossible to match tumors precisely, both groups were case-matched by overall stage, as well as matched as closely as possible for individual TNM stage and subsite of oropharyngeal involvement (Table I). In addition, although not all patients received radiation therapy as part of their treatment, overall treatment was similar across each stage for both treatment groups with similar proportions of patients receiving adjuvant radiotherapy (Table II). Except for patients with stage II disease and those with recurrent or persistent disease after prior radiotherapy, most patients in both groups with stages III and IV disease received postoperative irradiation. Given the similar staging and treatment distribution between transhyoid and mandibulotomy groups, some basis exists for valid comparison between these groups.
Although we have found the transhyoid approach to be suitable for many tumors affecting the tongue base and tonsillar regions, as with any surgical approach, there are certainly limitations with this approach that deserve mention. By reviewing those cases mentioned previously in which the tumor was initially assessed via a transhyoid fashion but eventually required division or segmental resection of the mandible, some of these limits can be appreciated. Of the 11 cases in which this situation occurred, all had advanced-stage disease at the primary site or recurrent disease. Interestingly, nearly two thirds of these cases (seven patients) had T4 disease primarily involving the tonsillar fossa and were found to have mandibular involvement, deep pterygoid involvement, or extension toward the skull base requiring, in most instances, mandibular resection for adequate exposure and resection. In fact, of the 41 patients who underwent resection solely through the transhyoid approach, none had T4 tonsillar lesions. This observation suggests that, with findings of obvious mandibular involvement, deep pterygoid involvement or extension toward the skull base, resection solely via a transhyoid approach is inappropriate and that more traditional approaches that divide the mandible should be considered. As with these cases, however, initial tumor assessment via a transhyoid approach at the time of surgical exploration can be performed if these findings are in doubt before surgery.
With regard to surgical margins, the incidence of positive or close surgical margins was not found to be significantly different in the transhyoid group compared with the mandibulotomy group. In addition, no correlation was found between margin status and advancing T stage of disease (including recurrent disease). However, we were somewhat surprised at the overall incidence of positive or close margins found in both groups on final results of pathological examination, despite final negative results on intraoperative frozen-section analysis of control of tumor margins. This may be partly because of heavy reliance on intraoperative frozen-section analysis to determine final extent of resection and partly because of the fact that final margins, which are typically reported on only the main resection specimen, may not be truly representative of actual margin status, particularly in cases in which additional tissue was resected based on positive results of intraoperative frozen-section analysis. In this latter instance it is often difficult to reconcile, in a retrospective fashion, actual margin status using the pathology reports and operative records. Despite these findings, however, overall long-term survival was similar between groups—47% and 45% in the transhyoid and mandibulotomy groups, respectively. These rates are comparable to other reported rates in the literature for similarly staged disease. 14,15
Regional myocutaneous flaps have been used to achieve tension-free closure and re-establish tissue bulk in this region after tumor resection in an effort to reduce wound complications such as fistula formation and to maintain swallowing function. However, in the transhyoid group, most patients (38 of 41) underwent primary closure of their defect, with the use of regional myocutaneous flaps being significantly higher in the mandibulotomy group. This may in part reflect both changing surgeon preference and decreased wound complexity with this approach. Despite the use of primary closure in most patients in the transhyoid group, the fistula rate in the transhyoid group was actually significantly lower compared with the mandibulotomy group.
With regard to swallowing function, it can be argued that primary pharyngeal closure carries the potential for significant distortion of normal anatomical relationships, thus resulting in higher potential for postoperative dysphagia. However, levels of dysphagia in the transhyoid group were not significantly worse and were, in fact, similar in distribution to the levels observed in the mandibulotomy group. In both groups, approximately 80% of patients were able to eventually achieve adequate oral nutrition. As mentioned, most cases of severe dysphagia in both the transhyoid and mandibulotomy groups occurred in patients with either extensive disease (T4) at the primary site or recurrent or persistent disease after prior radiotherapy (14 of 15 patients). This finding is not particularly surprising, and it would appear logical that surgery for large-volume disease, as well as that for recurrent or persistent disease after prior radiotherapy, would carry significant impact on postoperative swallowing function.
One additional issue of potential importance with regard to postoperative function relates to the issue of mandibular reconstruction. Only six patients who underwent mandibular resection underwent primary reconstruction of their lateral mandibular defect—usually with a reconstruction plate. Four of these patients experienced moderate dysphagia after surgery, and one patient with a history of recurrent disease remained dependent on enteral nutrition via a feeding tube. Given relatively low numbers of patients, however, these results are difficult to interpret, and the impact of mandibular reconstruction on swallowing function cannot be reliably ascertained from this particular study.
Although the incidence of wound-related complications such as fistula formation was significantly higher in the mandibulotomy group, most notable was the difference in the incidence of osteoradionecrosis or osteomyelitis, which occurred with significantly greater frequency in the mandibulotomy group (7 of 41 patients) and only rarely in the transhyoid group (1 of 41 patients). Although events such as wound infection and fistula can often be rapidly controlled and effectively managed, the development of complications related to the mandible are often associated with significant long-term morbidity for the patient, because of symptoms such as pain and inability to masticate, and often require prolonged treatment. Based on these observations, and in the absence of a clear survival advantage, techniques that avoid division of the mandible when mandibular involvement is not present would seem preferable given the potential for reduced postoperative morbidity.
Resection of lesions via the transhyoid approach is a useful surgical adjunct that, in our experience, has afforded similar levels of postoperative swallowing function and comparable rates of long-term tumor control with reduced morbidity when compared with standard anterior approaches involving mandibular division or resection for similarly staged disease. Although a variety of even relatively advanced-stage primary lesions may be resected with this approach, lesions with significant mandibular or pterygoid involvement or skull base extension are probably inappropriate for transhyoid resection, because of inadequate exposure and the potential for oncological compromise. However, the overall favorable results of our experience have led us to continue to use this approach in the surgical treatment of cancer involving this region.