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Transoral Laser Microsurgery in Carcinomas ofthe Oral Cavity,Pharynx,and Larynx

Jochen A.Werner, MD, Anja A.Dnne, MD,

Benedik t J. Folz, MD, and Burkard M.Lipper t, MD

Background: Sin ce the int rodu cti on of l aser technology in the 1960s, use of the techn iqu e in treatin g

la r yn geal di seases has demonstr ated severa l advan tages over conventi onal r esecti ons in selected cases.

Methods:The au thor s review the publi shed data on oncologic laser sur ger y for the treatm ent of head and neck

car cin omas, and they also descri be their own clin ical experi ence w it h tr ansoral laser sur ger y for the treatment

of carcinomas of the oral cavity, pharynx, and lar ynx.

Results: Laser sur ger y has achi eved a key posit ion in m in im ally in vasive treatment concepts in the ear s, nose,

and throat ar ea, especia lly for the treatm ent of mali gnancies of the upper aerodi gesti ve tract. The CO2laser i s

the approach most comm only used.

Conclusions: New and improved appli cati ons of laser therapy in the treatm ent of cancer are bei ng explored.

As more su rgeons become experi enced i n the use of la ser s and as our kn ow ledge of the capab i li ti es and

advan tages of thi s tool expands, laser s may play a l ar ger role in the management of head an d neck cancer s.

The in dicati ons and

approach using

CO2laser surger y in

carcinomas of the

upper aerodigesti ve

tract are revi ewed.

Lu Jian Jun. The Dulcim er,2000. Oil on canvas,36 48. Courtesy of Weinstein Gallery,San Francisco, California.

From the Departm ent of Otolaryngology, Head an d Neck

Sur gery, Philipps Uni versity of Marbu rg, Germ any.

Subm itted Jun e 18, 2002; accepted August 5, 2002.

Address repri nt requests to Jochen A.Wern er, MD, Department

of Otolaryngology, Head an d Neck Sur gery, Philipps University

Marburg, Deutschhausstr. 3, 35037 Marburg, Germany. E-mai l :

j .a.wern er@mai ler.un i -ma rbu rg.de

No signi ficant relation shi p exists between t he author s and the

compani es/ organi zation s whose products or serv ices may be ref-

erenced i n t hi s ar ticle.

September/October 2002, Vol.9, No.5 Cancer Control 379

Introduction

The word laseris an acronym for light amplifica-tion by stimulated emission of radiation. Since theirdevelopment in 1960, lasers as surgical tools haveevolved and now play an important role in the diagno-sis and treatment of cancer. Laser treatment is moreprecise,decreases the change of infection,and reduceshealing time, bleeding, swelling,and scarring. Severallaser systems,such as the diode,ruby,Ho:YAG,Er:YAG,Nd:YAG,and yellow light lasers,as well as dye lasers for

photodynamic therapy,have been used for treating var-

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September/October 2002, Vol.9, No.5380Cancer Control

ious diseases. However, the argon and CO2 lasers werethe first laser systems to be clinically used in the treat-ment of otorhinolaryngology. The CO2 laser currentlyhas the greatest significance in otorhinolaryngology,

predominantly in the treatment of carcinomas of theupper aerodigestive tract.

Strong and Jako1 introduced the CO2 laser intomicrosurgery of the larynx in the early 1970s. The CO2laser was increasingly utilized in the 1980s in the treat-ment of benign lesions in the larynx,particularly recur-rent laryngeal papillomatosis. However, lasers wereintroduced more slowly in the treatment of malignan-cies and were restricted to only a few centers through-out the world. Furthermore, the application of laserswas mostly limited to the excision of early vocal cord

tumors. The first reports of the successful use of lasersin cancer surgery were published in 1975.2 Theirguidelines regarding the indications of laser tumorsurgery were carefully followed, with few alterations.Burian and Hfler were the first in Europe to success-fully treat a glottic carcinoma with the laser.3 As earlyas the beginning of the 1980s, Steiner1 expanded theindications for curative laser treatment to all regionsand all tumor types. This expansion was based on theexcellent results obtained with both the microsurgicallaser resection of early tumors and the palliation ofadvanced disease. Meanwhile, laser surgery achieved akey position in mini-mally invasive treat-ment concepts in theears, nose, and throat(ENT) area, especiallyfor the treatment ofmalignancies of theupper aerodigestivetract. In advancedcases,the primary aimof laser surgery is

organ preservation.1

Oral Carcinomas

The surgical approach and histologic con-firmation of clear margins for early stages oforal cancer differ slightly from those for otherregions within the upper aerodigestive tract.The areas involved by tumor are exposed withthe aid of gags and tongue depressors. Special

instruments can be used to optimize theaccess to the operative site. For instance,smallcarcinomas (1 or 1.5 cm in diameter) of thetongue are excised en bloc but with a relative-ly wide resection margin of 5 to 10 mm. Whenexcising the tumor, care must be taken tomaintain a uniform tumor margin in the deep-er muscular layers. If the superficial extension

of the tumor is greater than 10 mm in diameter or ifthere are signs of deep infiltration, one or more inci-sions can be made through the tumor,depending on itslocalization and extent (Fig 1). Transecting the tumor

may help to estimate more accurately the depth oftumor infiltration. These surgical steps are performedunder the operation microscope and are designed torender a higher level of oncologic safety in the excisionof these carcinomas.4,5

Mobi le Tongue and Floor of the Mouth

During laser microsurgical dissection, the tumor istraced into the surrounding healthy tissue regardless ofthe direction and degree of its extension. For carcino-mas of the floor of the mouth,two conditions deservea more detailed discussion (Fig 2). The first is the inclu-sion of excretory ducts of the sublingual and sub-mandibular glands into the resection; the second is themodification of the procedure if the mandible isinvolved. The excretory ducts of the lesser salivaryglands can be severed or partially resected. We rarelyobserve complications such as chronic inflammationwith intermittent swelling of the gland, which mayeventually necessitate the excision of the gland follow-ing laser microsurgical resection of oral carcinomas.This observation is explained by the fact that the mainexcretory duct is generally preserved in cases of super-

Fig 1. (A) T2 carcinoma of the right margin of the mobile tongue before laser micro-

surgery. (B) Good functional results are seen 24 months following laser microsurgery.

Fig 2. (A) T1 carcinoma of the floor of the mouth before microsurgery and (B) 16 months after laser microsurgery.

A B

A B

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September/October 2002,Vol.9, No.5382Cancer Control

the tonsil that still can be luxated. In these cases,tran-soral tumor tonsillectomy is performed (Fig 4). Largertumors in the area of the tonsil are resected in severalpieces as described by Steiner and Ambrosch.8 We per-form at least three horizontal incisions one superi-

orly, one through the middle, and one inferiorly. It isimportant to be aware of the depth of tumor extensionduring surgical procedures in the tonsillar area.Branches of the ascending palatine artery (from thefacial artery) and the descending palatine artery (fromthe maxillary artery),as well as branches of the ascend-ing pharyngeal artery, are ligated conventionally orwith vascular clips.

The glossotonsillar sulcus is another high-risk areafor deeper and more extensive resections involving larg-er arterial vessels such as the lingual artery and theexternal carotid artery. Other important structures inthe immediate proximity are the hypoglossal and glos-sopharyngeal nerves.The same safety precautions applyhere 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 aretreated with neoadjuvant radiochemotherapy. Six to 8weeks after radiochemotherapy, the tumor area isresected lasersurgically within the initial tumor border,and a unilateral or bilateral neck dissection is per-formed. To resect the tumor area properly, the tumorborder is tattooed initially during panendoscopy. In ourexperience with a limited number of patients,laser sur-gical resection does not appear to be associated withdelayed wound healing or an increase in the number ofcomplications with regard to the functional outcome.Our results suggest that further investigation involving alarger number of patients is warranted.

Base of Tongue and Val lecu la

A number of factors complicate the technicallysimple laser resection of carcinomas of the tongue.The

relatively common tumor extensions, especially into

the submucosal space, areoncologically unfavorablecharacteristics of thesecancers. Identification ofthe tumor borders is moredifficult in the tongue thanin the larynx. The morepronounced carbonization

encountered during lasersurgery of tongue tissue isa result of the increased

vascularization and theglandular tissue present inthe tongue.

Laser surgical treatment of cancer of the base ofthe tongue presents a challenge even for experiencedsurgeons. Apart from the postcricoid region, the baseof the tongue is the area of highest risk for endoscopicsurgery, especially if exposure through the bivalved

laryngoscope is not optimal. Also, differentiatingbetween tumor and healthy tissue can be particularlydifficult in the area of the tongue base due to obstruc-tion by the lingual tonsil. In addition, achieving ade-quate access to this region to allow sufficient exposureto all areas involved by tumor can be difficult. In manycases, the surgeon can see only a particular segmentand may lack any surrounding landmarks for orienta-tion, such as the pyriform sinus or larynx.

Laser surgical removal of the lingual tonsil may beof oncologic relevance in the diagnostic workup of can-cer of unknown primary (CUP syndrome). An occultprimary tumor would more likely be revealed if the sur-gical specimen were processed during pathohistologicexamination in serial sections rather than through ran-dom biopsies. In laser surgical resection of the lingualtonsil,care should be taken to avoid dissection into thelateral pharyngeal tissue or muscular layer, which mayincrease the risk of severe hemorrhage.

Laryngeal Carcinomas

The surgical, oncologic, and functional principlesare the same for minimally invasive surgery as for moreconventional resections. The primary objective is thecomplete resection of the tumor while preserving asmuch function as possible. The principle is to minimizesurgical morbidity while adhering to long-standingoncologic standards.

During transoral laser microsurgery, decisions aremade in accordance with the local spread of the tumor.The tumor extension is often clearly apparent under

the microscope,and the lesion is resected until healthy

Fig 4. (A) Small T2 carcinoma of the left tonsil before transoral laser microsurgery and (B) 22 months

following surgery.

A B

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tissue is found and appropriate safety margins can bemaintained.The goal of complete resection is achievedby variations in the surgical approach and dissectioninstrument. In general, a transoral approach is the pri-mary choice, and the CO2 laser under microscopic con-trol is used as a dissecting instrument.

All tumor surgery should adhere to the principle of

complete resection with clear surgical margins that arehistologically documented. This involves the coopera-tion of both the surgeon and the pathologist. Using asmall focal diameter of the laser beam results in mini-mal carbonization and is particularly suitable for thisapplication. The histologic assessment of the resectionmargins is facilitated by this technique, despite rela-tively close margins.9,10

The unconventional surgical technique of dissect-ing through larger tumors during the resection andremoving the tumor in parts allows the surgeon to

inspect the surface of the tissue under microscopiccontrol. There are no indications that the incidence oflate regional or distant metastases increases due to laserincisions through a tumor; this may be explained bythe sealing effect of the lymph vessels,which has beenobserved in previous investigations.11

Car cin oma In Situ , Mi croi nvasiveCarcinoma, and Small T1a Carcin omas

In cases of a biopsy-proven small carcinomas orcarcinoma in situ, the entire lesion is excised with anappropriate resection margin (Fig 5). When tumorinvade is found in the resection margin, two treatmentstrategies are possible: laser surgery or radiotherapy.We recommend repeating laser or conventional surgerybecause,in most cases where tissue is re-resected fromthe tumor margin, this tissue is tumor-free onhistopathologic investigation, and radiotherapy would

have been unnessecary. Our experience indicates that,in general, vocal function is almost normal followingsuch limited-excision biopsies.12

Large T1a and T1b Glotti c Car cinomas

When a clearly superficial lesion infiltrates to adepth of only approximately 2 mm and does not cover

the entire cord (ie, microcarcinoma), we excise thecarcinoma en bloc. When the depth of infiltration is indoubt, a single incision through the center of thetumor may help to estimate the depth. The subsequentlaser surgical treatment is the same as for small, well-circumscribed lesions. In cases of marginal involve-ment of the anterior commissure without subglotticextension, the anterior commissure is resected alongwith the bilateral cord lesion. The dissection is carriedout along the thyroid cartilage under high magnifica-tion of the operating microscope. Laser surgical resec-tions of carcinomas of the anterior commissure

require a surgeon experienced in this techniquebecause the risk of developing recurrent disease ismore likely in the anterior commissure than in anyother localization of the glottis.13-15

T2 Car cin omas

For all T2 carcinomas of the glottis, primary lasersurgery is advocated regardless of the pattern of tumorspread. Steiner16 reported that it is of no significancewhether the tumor is unilateral or bilateral,whether itextends to involve supraglottis or subglottis,or whetherit infiltrates the anterior commissure. Again,a surgeonwith wide experience in laser surgery is essential. Super-ficially spreading carcinomas are ideally suited for lasersurgery. Even if they cover vast areas of the endolarynx,they can be resected completely with a partial muco-sectomy of the larynx if the carcinoma can be exposedadequately.17 The excision can be performed in several

pieces,and the basal surfacesshould be stained with blueink for better orientation ofthe pathologist. Exact topo-graphic descriptions on thepathology request form areimportant and should becopied onto patient charts.Additionally, the exact originof the individual specimenmust be noted in a schematicdrawing of the larynx.

T3 Car cin omas

Currently,the majority of

resectable carcinomas are

Fig 5. (A) Intraoperative view of a T1a carcinoma of the left vocal cord before laser microsurgical resection

and (B) immediately after resection. (C) Two years postoperatively, no recurrent disease can be observed and

functional results are satisfactory.

A B C

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treated with conventional surgery.However,laser surgi-cal resection is feasible even for large tumors if theycan be exposed adequately and if the surgeon has therequired training in laser surgery. For these advancedtumors of the glottis, incisions are placed through thebulk of the tumor to divide it into smaller portions,lat-erally onto the thyroid cartilage and inferiorly onto thesuperior surface of the cricoid cartilage. Incisions fol-

low the extensions of the tumor and are placed deeplyinto the musculature until a tissue layer is encounteredthat reacts normally to the laser light under the micro-scope. If the musculature is invaded up to the peri-chondrium, the tumor can be resected by dissectingalong the inner table of the thyroid cartilage. Suspect-ed infiltration of the thyroid cartilage or definite pene-tration through parts of the cartilage is included in theresection. A specimen resected from the neighboringprelaryngeal soft tissues can be used to verify the com-pleteness of the resection. The resection of extendedcarcinomas should be performed by a surgeon experi-

enced in laser surgery to avoid an incomplete resectionthat would adversely affect the patients prognosis.Conventional surgery is preferred where an experi-enced surgeon is unavailable.

Supraglotti c Car cinomas

Small, well-circumscribed tumors of the supraglot-tis can be resected in one piece,similar to small lesionson the vocal cord.12

Suprahyoid Epiglottis and False Cord Area:Technically, tumors in this location can be easilyexcised. Wide resection margins can be achievedwithout functional implications as in the case ofglottic lesions.

Infrahyoid Epiglottis: The depth of tumor infil-tration in the area around the petiole is difficult toassess preoperatively. There may be considerable diffi-culty in distinguishing between a T1 tumor and a T3lesion (infiltration of the pre-epiglottic space). Todetermine the extent of the carcinoma to the pre-epiglottic space, we usually split the suprahyoidepiglottis sagitally.The bivalved laryngoscope is subse-quently advanced,thus revealing the surface of the dis-section plane through the epiglottic cartilage as well asthe pre-epiglottic fat and the laryngeal surface of theinfrahyoid epiglottis with the tumor. The tumor is thendissected in a sagittal plane. The dissection proceedsin an inferior direction. Depending on the extent ofthe tumor,horizontal cuts are placed through the bulkof the lesion. If the thyroid cartilage or one of the ary-tenoid cartilages is infiltrated by tumor,it is included inthe resection. During the resection of parts of the thy-

roid cartilage, care is taken to avoid damage to the

extralaryngeal vessels. If the tumor has brokenthrough the thyrohyoid membrane,it is followed as farinto the neck as possible. The resection can reach allthe way into the subcutaneous tissue of the neck. Per-sistent functional impairments are not anticipatedwith this surgery.

Resection of advanced carcinomas requires atten-

tion to postoperative function. Resection of one ary-tenoid cartilage is not associated with long-lasting func-tional impairment; however, if both arytenoids areresected, deglutition without aspiration is usually notpossible. Additional difficulties may occur if furtherresections in the area of the base of the tongue arerequired.18As already noted,the resection of extendedcarcinomas is reserved for surgeons with extensiveexperience with laser surgery.

Hypopharyngeal Carcinomas

The pretherapeutic assessment includes an endo-scopic examination (under general anesthesia) andcomputed tomography imaging. The results of theseinvestigations determine if a partial resection is possi-ble and justified. Tumor extension on the mucosal sur-face as seen by the examiner is rarely a reflection oftrue tumor extent. Carcinomas of the pyriform sinuscan invade the paraglottic and pre-epiglottic space,thearea of the arytenoid cartilages,the thyroid cartilage,orthe soft tissues of the neck without any evidence ofsuch invasion on endoscopy. Only extensive infiltration(for example, into the cricoarytenoid joint) will clini-cally indicate the deep invasion of the tumor byimpaired mobility or fixation of the arytenoid cartilage.

If laser surgical resection is indicated,a step-by-stepresection of the tumor in a craniocaudal direction isgenerally recommended. The tumor is removedblock-wiseand layer by layer. The dissection proceeds infe-riorly as far as good exposure and accessibility of thetissues in the dissection plane are assured. The tumoris divided into a mosaic-like pattern by horizontal and

vertical cuts. The border between tumor and healthytissue can be identified on the tissue section. Thebivalved laryngoscope is generally positioned so that amargin of normal tissue of approximately 10 mmremains between the blade of the speculum and theedge of the visible tumor. The incision into the mucosamust be made under the highest possible magnificationof the microscope.19

In summary, tumor and normal tissue can be par-ticularly well differentiated in the hypopharynx. Rela-tively wide resection margins of 5 to 10 mm can be

achieved in this area without major functional conse-

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quences caused by additional loss of tissue,thus result-ing in safer tumor resections. In all hypopharyngealtumors,spontaneous healing with complete epitheliza-tion of the wound occurs after their resection. Healingis usually complete within 6 weeks with good func-tional results.

Indications for Laser Applications inTumor Resection

Similar to the decision-making process in conven-tional surgery,determining the appropriate laser appli-cation for surgical resection of carcinomas of the upperaerodigestive tract, especially advanced carcinomas, isbased on thorough preoperative diagnostic criteria.When invasion of deeply located structures or extrala-ryngeal tumor spread is evident on computed tomogra-phy scans or magnetic resonance images,a laser surgi-cal approach is appropriate,but only in the hands of

experienced surgeons. Compared with the surgicalskill needed to resect a tumor through an openapproach with an open surgical field and excellentexposure, a higher level of expertise is required toachieve good oncologic results in resecting inaccessi-ble carcinomas or advanced laryngeal and pharyngealcarcinomas through a progressively narrow endoscope.This skill level is particularly necessary if the tumormust be resected endoscopically in several portions.These cases illustrate the need for intensive training inendoscopic laser surgery in order to achieve soundoncologic results with laryngeal and pharyngeal lasermicrosurgery. The functional and oncologic outcomesobtained with this technique closely correlate to theexperience of the surgeon. A conventional surgicalapproach should be chosen if the tumor is too difficultto expose or the surgeon has only limited experiencewith laser surgery in advanced carcinomas.

Therapeutic Concept BeyondLaser Surgery

With regard to the prognosis of patients withhead and neck cancers, therapy of the lymphatic sys-tem is of primary importance. Adequate treatment ofthe clinically node-negative neck (N0 neck) is the cen-tral point of controversy. At present, there is no uni-formly accepted standard for the surgical treatment ofthe N0 neck in carcinomas of the head and neck. Rec-ommendations range from no surgical interventionbut with strict follow-up control, to a limited selectiveneck dissection as a solitary therapeutic measure evenwith histologic proof of metastases, or to a modifiedradical neck dissection in N0 necks and localized

primary tumors.

Given the variability in treatment concepts amongoncologic centers,certain guidelines need to be recog-nized. From our viewpoint, adopting await-and-seestrategy rather than selective neck dissection may be

justified in patients with a reliable compliance and incenters with broad expertise in ultrasonography imag-ing of the neck. With regard to surgical treatment,weanticipate that selective neck dissection will gain more

acceptance in treating the N0 neck than modified radi-cal neck dissection. The extent of selective neck dis-section is determined by the localization of the tumorwhether it is localized unilaterally or whether itreaches the midline or even expands over the midline.

An exception to this strategy is T1 carcinoma of thevocal cord. A similar approach is currently supportedin the literature for T2 glottic carcinoma.16 However,advanced T2 glottic carcinoma,a low grade of differen-tiation of the primary tumor, as well as lymphangitiscarcinomatosa, may warrant selective neck dissectionin certain cases (levels II-III and possibly even level IV)

even in these selected T2 glottic carcinomas cases. Forall other tumor locations of the oral cavity,pharynx,andlarynx,we currently recommend selective neck dissec-tion. This usually includes levels I-III in carcinomas ofthe oral cavity and levels II-IV in oropharyngeal, laryn-geal,and hypopharyngeal carcinomas.

Optimal therapy of the clinical N1 neck is also acontroversial issue. In cases of glottic or hypopharyn-geal carcinomas,consideration should be given to alter-ing the modified radical neck dissection to ensure thatlymph nodes of level I remain intact. However, in theclinical N2 neck,there is general consensus that a mod-ified radical neck dissection should be performed.

In cases of a representative node dissection with ahistologically proven N0 neck or single,isolated lymphnode metastasis without extranodal spread or lym-phangitis carcinomatosa, we do not include adjuvantradio-chemotherapy in cases of total laser microsurgi-cal resection of the primary.

Neck dissection is one technique that can beutilized within the context of the laser surgical prima-ry resection or as a second-line approach. Steiner16

often used the second-line approach with an intervalof approximately 1 week between tumor resectionand neck dissection. As a result of intensive investiga-tions on the role of the sentinel node concept forsquamous cell carcinoma of the upper aerodigestivetract,20,21 we perform neck dissections as single-stageprocedures parallel to laser surgical resections ofthe primary tumor in N0 neck cases because validityof the intraoperative proof of the initially draininglymph node correlates closely to the physiologic

lymphatic drainage.

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References

1. Strong MS,Jako GJ. Laser surgery in the larynx: early clinicalexperience with continuous CO2 laser. Ann Otol Rhin ol Laryngol.1972;81:791-798.

2. Strong MS. Laser excision of carcinoma of the larynx. Laryn-goscope. 1975;85:1286-1289.

3. Burian K, Hfler H. On micirosurgical treatment of vocalcord carcinomas with CO2 laser. Laryn gol Rhin ol Otol (Stut tg).1979;58:551-556.

4. Steiner W,Werner JA, eds. Laser s in Otorhi nola r yngology,Head and Neck Sur ger y. Tuttlingen: Endo-Press; 2000.5. Jckel M,Steiner W. Ear,nose and throat techniques in endo-

luminal surgery. Min im Invasive Ther. 1998;7:9-14.6. Steiner W, Aurbach G, Ambrosch P. Minimally invasive thera-

py in otorhinolaryngology head and neck surgery. Minim InvasiveTher. 1991;1,57-70.

7. Rudert H,Werner JA, Hft S. Transoral carbon dioxide laserresections of supraglottic carcinomas. Ann Otol Rhin ol Laryngol.1999;108:819-827.

8. Steiner W, Ambrosch P, eds. Endoscopi c Laser Sur ger y ofthe Upper Aerodi gestive Tract: With Special Emphasis on Cancer

Su rgery. Stuttgart,New York: Thieme; 2000.9. Rudert H,Werner JA. Partial endoscopic resection with the

CO2 laser in laryngeal cancer. I. Resection techniques [German].Laryngorhinootologie. 1994;73:71-77.

10. Rudert H,Werner JA. Partial endoscopic resection with theCO2 laser in laryngeal carcinomas. II. Results [German]. Laryn-gorhinootologie. 1995;74:294-299.

11. Werner JA,Lippert BM,Schnke M,et al. Animal experimentstudies of laser effects on lymphatic vessels: a contribution to the dis-cussion of laser surgery segmental resection of carcinomas [Ger-man]. Laryngorhinootologie. 1995;74:748-755.

12. Rudert H,Werner JA. Endoscopic resections of glottic andsupraglottic carcinomas with the CO2 laser. Eur Arch Otorhin o-laryngol. 1995;252:146-148.

13. Eckel HE,Schneider C,Jungehulsing M,et al. Potential role oftransoral laser surgery for larynx carcinoma. Lasers Surg Med.1998;23:79-86.

14. Eckel HE. Local recurrences following transoral laser surgeryfor early glottic carcinoma: frequency, management, and outcome.Ann Otol Rhinol Lar yngol. 2001;110:7-15.

15. Puxeddu R,Argiolas F, Bielamowicz S,et al. Surgical therapyof T1 and selected cases of T2 glottic carcinoma: cordectomy, hori-zontal glottectomy and CO2 laser endoscopic resection. Tumori.2000;86:277-282.

16. Steiner W. Results of curative laser microsurgery of laryngealcarcinomas. Am J Otolar yngol. 1993;14:116-121.

17. Werner JA,Dnne AA,Folz BJ,et al. Laser surgery for T2 glot-tic carcinoma. Otorhinolar yngol Nova. 2002. In press.

18. Werner JA,Steiner W. Endoscopic laser treatment of laryngealand tracheal diseases. In: Berlien HP, ed. Appli ed Laser Medi cine.Berlin: Springer; 2002. In press.

19. Steiner W,Ambrosch P,Hess CF,et al. Organ Preservation bytransoral laser microsurgery in pyriform sinus carcinoma. Otolaryn-gol Head Neck Sur g. 2001;124:58-67.

20. Werner JA,Dnne AA,Ramaswamy A,et al. The sentinel nodedetection in N0 cancer of the pharynx and larynx. Br J Cancer.2002. In press.

21. Werner JA,Dnne AA,Ramaswamy A,et el. Number and loca-tion of radiolabeled, intraoperatively identified sentinel nodes in 48head and neck cancer patients with clinically staged N0 and N1 neck.Eur Ar ch Otorhin olaryn gol. 2002;259:91-96.

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