Efficacy of the Supraomohyoid Neck Dissection in the Control of the Lymphatic Metastases of Oral squamous Cell Carcinoma

ORIGINAL PAPERS Dent. Med. Probl. 2008, 45, 1, 13 20 ISSN 1644 387X Copyright by Silesian Piasts University of Medicine in Wrocław and Polish Stomatological Association MARCIN KOS 1, KLAUDIUSZ ŁUCZAK 2 Efficacy of the Supraomohyoid Neck Dissection in the Control of the Lymphatic Metastases of Oral squamous Cell Carcinoma Skuteczność limfangiektomii nadgnykowej w kontroli przerzutów szyjnych raka płaskonabłonkowego jamy ustnej 1 Department of Maxillofacial Surgery Klinikum Minden, Germany 2 Department of Maxillofacial Surgery Silesian Piasts University of Medicine in Wrocław, Poland Abstract Background. Metastasising of the oral squamous cell carcinoma (OSCC) to the cervical lymph nodes constitutes a significant prognostic factor. Thus, the control of lymphatic spreading of the disease has become one of the strate gic points of the OSCC treatment. However, it is still an unresolved controversy to what extension the lymph nodes should be removed and whether operation alone or in combination with radiotherapy fulfils the best requirements of the oncological radicality providing an acceptable morbidity at the same time Objectives. Assessment whether the supraomohyoid neck dissection (SOND) is efficient in the control of the lym phatic spreading of oral cancer. Material and Methods. A retrospective study on 48 patients treated from 1.01.2000 to 31.12.2006 with SOND as the primary neck procedure. Totally, 73 SOND were performed including 25 patients operated bilaterally. In 22/48 (45,8%) cases, radiotherapy followed surgery on account of: neck metastases (11), T 3, T 4 tumours (12), R 1 resec tion (5), G 3 histological malignancy (8), or unfavourable localisation (4). In several instances, irradiation was jus tified by more than one reason. The efficiency of the neck treatment with and without metastases was based on the assessment of the number of ipsilateral and contralateral recurrences, disease free survival, overall survival rate, and the frequency of skip metastases in the level IV. The survivals were estimated with Kaplan Meier method. The log rank test was used in order to compare the difference between the groups. Results. The ipsilateral recurrence appeared in 8.3%. No contralateral relapses and no skip metastases to the level IV were observed. Disease free survival amounted to 40.1% during 5 year observation. Its value for the patients with positive lymph nodes but additionally irradiated (56.8%) was higher than for those with negative ones and those only observed (33.7%; p = 0.53). The overall survival rate for the whole study group amounted to 85.7% within 5 years. In overall survival, no difference was observed between the patients with and without neck metas tases (p = 0.811). Conclusion. Supraomohyoid neck dissection, supported by radiotherapy in selected cases, is a safe, efficient and not mutilating option for patients treated for oral cancer (Dent. Med. Probl. 2008, 45, 1, 13 20). Key words: supraomohyoid neck dissection, oral squamous cell carcinoma, regional control. Streszczenie Wprowadzenie. Obecność przerzutów raka jamy ustnej do węzłów chłonnych szyi jest ważnym czynnikiem pro gnostycznym. Dlatego kontrola rozprzestrzeniania się choroby drogą limfatyczną jest jednym ze strategicznych punktów leczenia. Zakres resekcji w obrębie układu chłonnego oraz konieczność stosowania uzupełniającej radio terapii są wciąż tematem dyskusji w związku z koniecznością pogodzenia optymalnej radykalności onkologicznej z minimalizacją skutków ubocznych. Cel pracy. Ocena, czy oszczędzająca operacja, jaką jest limfangiektomia nadgnykowa, jest skuteczną metodą kon troli rozprzestrzeniania się raka płaskonabłonkowego jamy ustnej drogą limfatyczną. Materiał i metody. Retrospektywna analiza wyników leczenia 48 pacjentów hospitalizowanych w okresie od 1 stycznia 2000 r. do 31 grudnia 2006 r. Sumarycznie wykonano 73 limfangiektomie nadgnykowe, włączając w to 25 pacjentów operowanych obustronnie. W 22/48 (45,8%) przypadków przeprowadzono uzupełniającą radiotera

14 M. KOS, K. ŁUCZAK pię z powodu obecności przerzutów do węzłów chłonnych szyi (11), T 3 T 4 miejscowego zaawansowania (12), mi kroskopowo nieradykalnej resekcji (5), wysokiego (G 3 ) stopnia histologicznej złośliwości (8), niekorzystnego umiejscowienia guza (4). W kilkunastu przypadkach radioterapia była podyktowana wieloma względami. Ocenę skuteczności leczenia oparto na analizie liczby nawrotów szyjnych po stronie guza, liczby nawrotów przeciwstron nych, czasu przeżycia bez nawrotu choroby, czasu całkowitego przeżycia oraz częstości bezpośrednich przerzutów do strefy IV. Czasy przeżycia szacowano metodą Kaplana Meiera. Do porównania różnic między grupami użyto testu regresji logistycznej. Wyniki. W 8,3% przypadków wystąpiły przerzuty po stronie guza. Nie zaobserwowano obecności przerzutów przeciwstronnych lub bezpośrednich do obszaru IV. Odsetek 5 letnich przeżyć bez nawrotu choroby wynosił 40,1%. U pacjentów z przerzutami do węzłów chłonnych szyi, lecz dodatkowo naswietlanych, był on większy (56,8%) niż u osobników z pierwotnie niezajętymi węzłami, u których odstąpiono od radioterapii (33,7%; p = 0,53). Odsetek całkowitego czasu przeżycia dla badanej grupy wynosił 85,7% i nie różnił się statystycznie u pacjentów z przerzutami i bez przerzutów szyjnych (p = 0,811). Wniosek. Limfangiektomia nadgnykowa, wsparta w uzasadnionych przypadkach radioterapią, jest bezpieczną, skuteczną i nieokaleczającą propozycją terapeutyczną dla pacjentów chorych na raka jamy ustnej (Dent. Med. Probl. 2008, 45, 1, 13 20). Słowa kluczowe: limfangiektomia nadgnykowa, rak płaskonabłonkowy jamy ustnej, kontrola regionalna. Metastasising of the oral squamous cell carci noma (OSCC) to the cervical lymph nodes consti tutes a significant prognostic factor [1, 2]. In the view of that, the control of lymphatic spreading of the disease has become one of the strategic points of the OSCC treatment [3]. Various therapeutic approaches are available as far as the neck man agement is concerned: observation, radiotherapy, surgery or the combination of all of the above. [4]. Radical neck dissection (RND), first described by Crile in 1906, has been a substantial method of the neck control in head and neck carcinomas, for many years [5, 6]. It accomplishes resection of all of the cervical structures believed to be involved in metastatic disease. Unfortunately removal of the sternocleidomastoid muscle, internal jugular vein and spinal accessory nerve produces a signif icant postoperative morbidity with shoulder dys function, pain, restriction of head motility, and unacceptable cosmetic results [6, 7]. A disappoint ing number of recurrences (despite the extensive ness of the surgery), better understanding of the anatomy of neck fascial compartments, and a pat tern of lymphatic drainage as well as the impor tance of the quality of life after modern oncologi cal treatment have influenced evolution of the surgery towards less mutilating techniques with preservation of all non lymphatic and selected lymphatic structures [3, 7 9]. However, it is still an unresolved controversy to what extension the lymph nodes should be removed and whether operation alone or in combination with radiothera py fulfils the best requirements of the oncological radicality providing an acceptable morbidity at the same time [10 12]. It is believed that patients without nodal involvement do not benefit from irradation and should not be unnecessarily treated [1, 2]. As a result of a high unreliability of preoperative clin ical and radiological diagnostic in predicting of the nodal status a surgery must take over the role of a staging procedure [13]. Consequently, an attention has been drawn to supraomohyoid neck dissection (SOND), which encompasses the removal of the I III lymph node echelons [9, 14]. The lymph node groups to be removed are adequate to the predictable pattern of metastases for oral cancer with respect to frequen cy of direct invasion of level IV [4, 15, 16]. Until now, SOND has gained an acceptance mainly in researches on highly selected groups of patients and there are still existing controversies about its use as a standard procedure especially in positive necks [11, 17, 18]. The present study was undertaken to determine the efficiency of a clinical algorithm in which SOND, accompanied by radio therapy, was used as a standard method to control the lymphatic spreading of oral cancer. Material and Methods This research was based on a retrospective group of 48 patients treated with OSCC from 1st January 2000 to 31st December 2006. All patients underwent SOND as the primary neck procedure. Totally, 73 SOND were performed including 25 patients operated bilaterally. Their characteristics is presented in Table 1. Radiotherapy followed surgery in 22/48 (45,8%) of the cases in the pres ence of: neck metastases (11), T 3, T 4 tumour advancement (12), after not radical (R 1 ) tumour excision (5), as a consequence of a high grade (G 3 ) of histological malignancy (8), and unfavourable localisation in the base of tongue or oropharynx (4). In some cases, irradiation was justified by more than one reason. The efficiency of the treat ment, in cases with and without neck metastases,

Efficiacy of the Supraomohyoid Neck Dissection 15 was based on the assessment of the number of ipsi lateral and contralateral neck recurrences, disease free survival, overall survival rate, and frequency of skip metastases in the level IV. Disease free survival was defined as the period form the end of the surgery to the first recurrence or the second primary. The overall survival rate was defined as the percentage of the patients who were alive for more than 5 years divided by the total number of the patients. Estimation of the above mentioned parameters was made by the use of the Kaplan Meier method. The log rank test was employed in order to compare the difference between the groups. Statistical significance was defined as p < 0.05. Statistical analysis was done with SPSS for Windows 14.0 (SPSS Inc, Chicago, USA, IL). Results The results of the study are displayed in the Table 2. Despite more advanced disease, any cer vical recurrences did not appear as regards the patients with postoperatively positive lymph nodes which were submitted to adjuvant irradiation. The metastases concerned only the initially negative necks. The difference between both series was sta tistically insignificant (Fig. 1). There were 2 early and 2 late recurrences (Table 1). In all cases a local relapse preceded neck metastases. There were not any contralateral neck metas tases and any skip metastases to the level IV in the study group. Disease free survival presented a dropping profile with stabilisation at 40.1% calculated for 5 year observation (Fig. 2). Its value for the patients with neck metastases but additionally irra diated (56.8%) was higher than for those with neg ative lymph nodes which were only observed (33.7%) (Fig. 3). Although this difference could not be statistically confirmed, it suggests an important role of adjuvant radiotherapy in the management of patients with oral cancer. The overall survival rate for the whole study group amounted to 85,7% within 5 years. There was no difference in overall survival between the patients with and without neck metastases (Fig. 4). Discussion The control of the neck metastases constitutes an important part of the OSCC management and influences the final outcome considerably [1, 12]. The neck observation alone should be avoided as a consequence of significantly worse prognosis in patients with occult metastases [10, 19, 20]. It is strongly suggested that neck dissection or irradia tion should be performed in patients treated with OSCC; however, the exact type of the manage ment has not been clearly defined yet. In our study, the total number of the ipsilater al neck recurrences run into a level of 8,3%; nev ertheless, they appeared exclusively in cases that were only observed due to the negative lymph node status. Those with positive histopathology, submitted to radiation, surprisingly did not reveal any neck recurrences. It emphasises the impor tance of radiotherapy in modern oncological treat ment and shows that the surgery alone is not suffi cient for the regional neck control resulting in 10.8% recurrence rate. It could be speculated, as the half of these relapses appeared at the end of the five year observation period (54 and 57 months after operation), that they could have been ascribed to the development of the secondary tumours thus reducing the recurrence rate to 5%. However, keeping strictly a 5 year oncological survival criterion, the recurrence rate in non radi ated patients must be considered too high. Only association of the surgery and the radiotherapy in our treatment regimen led to an acceptable number of ipsilateral neck recurrences. Kokemueller et al., in review based on 373 OSCC treated with differ ent types of modified RND, report about 82 95% control rate [6]. Efficiency of modified RND with preservation of spinal accessory nerve was com pared with SOND in the report of Brazilian Head and Neck Cancer Study Group. Both surgeries were followed by irradiation of positive necks. Such therapeutic scheme was burdened with 10.3% and 6.9% ipsilateral neck recurrence rate respectively [21]. In the series of Duvvuri et al. a 7% ipsilateral failure was found after RND among 142 T 2 patients with oral cancer. Postoperative irradiation supplemented the man agement of cases presenting positive nodes, close resection margins and perineural invasion of the tumour [23]. A RND in the report of Yu et al. was complicated with 5% ipsilateral neck recurrence rate comparing with 4.7% failure for SOND [10]. In the combination with radiotherapy, SOND evolves rather into a staging procedure than thera peutic one, allowing to selection of the patients requiring additional treatment. The problem of a treatment option in the cases of extracapsular spreading of lymph node metastases requires fur ther research and confirmation as such events were not observed in our material. Whether the level IV of lymph nodes should be removed during neck dissection in patients suf fering from oral cancer remains under discussion [15, 16]. The reported incidence of failure at level IV in the absence of nodal involvement of levels I

Table 1. Characteristics of the study group Tabela 1. Charakterystyka kliniczna badanej grupy Nr Sex Age Tumour location Tumour advancement pn Radiation Disease free Overall Comments (Lp.) (Płeć) years (Umiejscowienie) (Zaawansowanie) (Naświetlanie) survival months survival (Uwagi) (Wiek (Czas przeżycia bez months lata) objawów choroby (Całkowity miesiące) czas przeżycia miesiące) 1 w 59 palatoglossal arch right pt 1 pr 0 G 1/2 0 0 40 40 2 m 58 mouth floor anterior and right pt 2 pr 0 G 2 0 0 26 26 3 m 66 tongue left pt1 pr1 G2 1 1 3 60 local recurrence 4 m 56 mouth floor anterior and right pt 3 pr 0 G 2 0 1 32 32 5 m 71 tongue left pt 2 pr 0 G 2 0 0 28 28 local recurrence 6 m 76 tongue, retromolar triangle left pt 1 pr 0 G 3 2b 1 12 12 7 m 53 tongue right pt1 pr0 G1 0 0 27 27 death of cerebral insult 8 m 55 base of tongue right pt2 pr0 G2 0 1 6 6 local recurrence, death of tumour 9 m 63 retromolar triangle, hard palate left pt2 pr0 G2 1 1 48 48 local recurrence, death of tumour 10 w 65 oropharynx left pt 2 pr 1 G 2 0 1 17 29 local recurrence 11 m 36 tongue right pt 1 pr 0 G 2 0 0 47 47 12 m 53 tongue left, mouth floor pt4 pr0 G2/3 0 1 61 69 second primary cancer 13 w 87 mouth floor right, mandibular gingiva pt2 pr0 G3 0 0 3 3 14 m 65 base of tongue right pt2 pr0 G2 2a 1 79 72 15 w 71 mouth floor, cheek, gingiva right pt 4 pr 0 G 1 0 1 25 25 16 w 66 tongue right pt 2 pr 0 G 3 0 0 17 17 17 w 63 mouth floor anterior pt3 pr0 G2 0 1 65 65 18 m 64 mouth floor, tongue left pt2 pr0 G2 0 0 33 33 19 w 63 mouth floor left pt1 pr0 G1/2 0 0 44 44 20 m 60 mouth floor right pt 4 pr 0 G 2 1 1 65 65 21 m 76 tongue right pt 1 pr 0 G 2 0 0 31 31 22 w 46 tongue right pt2 pr0 G3 0 0 10 13 local and regional recurrence 23 w 70 cheek right, mandibular involvement pt4 pr1 G2 0 1 6 6 local recurrence 24 m 48 mouth floor anterior pt 1 pr 0 G 2 0 0 78 72

25 m 60 tongue left pt2 pr0 G1 0 0 3 3 26 w 54 mouth floor anterior pt4 pr0 G1 2b 1 60 60 27 m 56 hard palate pt 2 pr 0 G 2 1 1 10 10 local recurrence 28 m 66 tongue right pt3 pr0 G2 0 1 6 10 local recurrence 29 m 65 mouth floor anterior pt1 pr0 G2 0 0 9 9 30 w 60 tongue right pt2 pr0 G2 2b 1 54 72 local recurrence 31 m 64 cheek, gingiva, mouth floor pt3 pr1m1 G 1/2 0 1 36 36 32 m 64 retromolar triangle right pt2 pr0 G3 0 0 15 15 local recurrence, death of tumour 33 m 56 tongue right, base of tongue pt3 pr1 G3 1 1 7 7 34 m 67 mouth floor left, tongue, soft palate pt3 pr0 G3 0 1 6 10 local recurrence, death of tumour 35 m 47 mouth floor left pt1 pr0 G2 1 1 54 54 36 w 36 tongue right pt 1 pr 0 G 1/2 0 0 46 46 37 w 69 maxilla, cheek right pt2 pr0 G1/2 0 0 11 11 38 m 65 mouth floor anterior pt0 pr0 G1 0 0 10 10 39 m 36 mouth floor anterior pt2 pr0 G2 0 0 72 72 40 m 38 tongue left pt 1 pr 0 G 2 0 0 13 13 41 m 67 mouth floor anterior pt 1 pr 0 G 2 0 0 54 54 loco regional recurrence 42 w 67 tongue right pt1 pr0 G2 0 0 7 7 43 m 55 mouth floor left pt2 pr0 G2 0 0 10 10 44 w 62 mouth floor left pt1 pr0 G1/2 0 0 57 60 loco regional recurrence 45 w 64 tongue, palatoglossal arch right pt 1 pr 0 G 2 0 0 18 21 loco regional recurrence 46 w 78 maxilla left pt 2 pr 0 G 2 0 1 15 60 local recurrence 47 w 25 tongue left pt2 pr0 G2 0 0 28 28 48 m 64 mouth floor anterior and left pt 4 pr 0 G 2 1 1 60 60 59,9 (12) 4 Mean SD. Średnia odchylenie standardowe.

18 M. KOS, K. ŁUCZAK Table 2. Recurrences and survivals in the studied group of patients Tabela 2. Liczba nawrotów i czas przeżycia w badanej grupie pacjentów Ipsilateral Contralateral Skip metastases Disease free Overall survival recurrence rate recurrence rate (Przerzuty survival 1 rate 2 (Liczba nawro (Liczba nawro bezpośrednie) (Czas przeżycia (Całkowity tów po stronie tów po stronie bez objawów czas przeżycia 2 ) guza) przeciwnej) choroby 1 ) % % pn 0 4/37 (10,8%) 0/37 0/37 33,7 90,4 pn+ 0/11 0/11 0/11 56,8 85,4 Total in 4/48 (8,3%) 0/48 0/48 40,1 85,7 the study pn 0 patients without cervical metastases. pn+ patients with cervical metastases. 1, 2 cumulative survival at 5 year observation period. pn 0 pacjenci bez przerzutów szyjnych. pn+ pacjenci z przerzutami do węzłów chłonnych szyi. 1, 2 skumulowane przeżycia przy 5 letnim okresie obserwacji. cumulative survival skumulowane prze ycie cumulative survival skumulowane prze ycie overall survival ca³kowity czas prze ycia p = 0.122 disease free survival czas prze ycia bez nawrotu choroby observation time months czas obserwacji miesi¹ce Fig. 1. Difference in the ipsilateral neck recurrence rate between irradiated (presenting lymph node metas tases; pn+) and non radiated (without neck metas tases; pn 0 ) patients Ryc. 1. Różnica w liczbie nawrotów szyjnych między pacjentami poddanymi radioterapii (z przerzutami w węzłach chłonnych szyi; pn+) i nienaświetlanymi (bez przerzutów węzłowych; pn 0 ) through III varies between 0.5 and 2.6% [4, 10, 16, 23]. No skip metastases were observed during our study. No final conclusion could be drown in the view of too small number of cases. None theless, a small likelihood of failure at level IV fol lowing SOND was stated providing that this surgery supported with radiotherapy is a safe and efficient operation. Similarly there were not any recurrences at the contralateral neck after our treatment regimen. In the literature, the affection observation time months czas obserwacji miesi¹ce Fig. 2. Overall survival rate and disease free survival in the whole study group Ryc. 2. Całkowity czas przeżycia i czas przeżycia bez nawrotu choroby w badanej grupie pacjentów of the contarlateral side is estimated at 0.5 2.8% [10, 19, 21, 23]. Disease free survival and the overall survival rate parameters are widely applied for description of the quality of oncological treatment. In this research, disease free survival was estimated at 40.1% for 5 year observation period. It correlates favourably with the reports of other authors con cerning elective or radical neck dissections [10, 22]. Disease free survival of the patients with neck metastases whereas additionally irradiated was higher than those with negative lymph nodes which were only observed. Although this differ ence could not be statistically confirmed, it again

Efficiacy of the Supraomohyoid Neck Dissection 19 cumulative survival skumulowane prze ycie cumulative survival skumulowane prze ycie p = 0.53 p = 0.811 observation time months czas obserwacji miesi¹ce Fig. 3. Comparison of disease free survivals between patients with (pn+) and without neck metastases (pn 0 ) Ryc. 3. Porównanie czasów przeżycia bez nawrotu choroby między pacjentami z przerzutami szyjnymi (pn+) i bez przerzutów węzłowych (pn 0 ) suggests an importance of combination of the surgery and radiotherapy in the management of patients with OSCC. In our study, the overall sur vival rate amounted to 85.4% during 5 years. In the report of Duvvuri et al., it is running consider ably under 70% within the same time of observa tion [23]. Yu et al. estimated this parameter at 68% for RND and at 75% for SOND [10]. The prospec tive trial of Brazilian Head and Neck Cancer Study Group on modified RND vs. SOND in the man agement of OSCC showed that overall 5 year sur vivals were equal for both procedures and amount ed to 63% and 67% respectively [21]. The com observation time months czas obserwacji miesi¹ce Fig. 4. Comparison of overall survival rates between patients with (pn+) and without neck metastases (pn 0 ) Ryc. 4. Porównanie całkowitych czasów przeżycia między pacjentami z przerzutami szyjnymi (pn+) i bez przerzutów węzłowych (pn 0 ) parison of the disease free and overall survivals illustrates that there is no superiority of RND over SOND including the events of histologically posi tive nodes. The authors concluded that supraomohyoid neck dissection, supported with radiotherapy in selected cases, is safe and efficient treatment option for the patients suffering from cancer of the oral cavity. The procedure offers an equal onco logical effectiveness as radical neck dissection, but allows avoiding a mutilating surgery. References [1] CHONE C. T., SILVA A.R., CRESPO A. N., SCHLUPP W.R.: Regional tumour recurrence after supraomohyoid neck dissection. Arch. Otolaryngol. Head Neck Surg. 2003, 129, 54 58. [2] ZBAREN P., NUYENS M., CAVERSACCIO M., STAUFFER E.: Elective neck dissection for carcinomas of the oral cavi ty: occult metastases, neck recurrences, and adjuvant treatment of pathologically positive necks. Am. J. Surg. 2006, 191, 756 760. [3] SIVANANDAN R., KAPLAN M. J., LEE K. J., LEBL D., PINTO H., LE Q. T.: Long term results of 100 consecutive com prehensive neck dissections: implications for selective neck dissections. Arch. Otolaryngol. Head Neck Surg. 2004, 130, 1369 1373. [4] O BRIEN C. J., TRAYNOR S. J., MCNEIL E., MCMAHON J. D., CHAPLIN J. M.: The use of clinical criteria alone in the management of the clinically negative neck among patients with squamous cell carcinoma of the oral cavity and oropharynx. Arch. Otolaryngol. Head Neck Surg. 2000, 126, 360 365. [5] SANTOS A. B., CERNEA C. R., INOUE M., FERRAZ A. R.: Selective neck dissection for node positive necks in patients with head and neck squamous cell carcinoma: a word of caution. Arch. Otolaryngol. Head Neck Surg. 2006, 132, 79 81. [6] KOKEMUELLER H., BRACHVOGEL P., ECKARDT A., HAUSAMEN J. E.: Neck dissection in oral cancer clinical review and analysis of prognostic factors. Int. J. Oral Maxillofac. Surg. 2002, 31, 608 614. [7] FERLITO A., RINALDO A., ROBBINS K. T., LEEMANS C. R., SHAH J. P., SHAHA A. R.: Changing concepts in the sur gical management of the cervical node metastasis. Oral Oncol. 2003, 39, 429 435. [8] ANDERSEN P. E., WARREN F., SPIRO J., BURNINGHAM A., WONG R., WAX M. K.: Results of selective neck dissec tion in management of the node positive neck. Arch. Otolaryngol. Head Neck Surg. 2002, 128, 1180 1184.

20 M. KOS, K. ŁUCZAK [9] WOOLGAR J. A.: The topography of cervical lymph node metastases revisited: the histological findings in 526 sides of neck dissection from 439 previously untreated patients. Int. J. Oral. Maxillofac. Surg. 2007, 36, 219 225. [10] YU S., LI J., LI Z., ZHANG W., ZHAO J.: Efficacy of supraomohyoid neck dissection in patients with oral squamous cell carcinoma and negative neck. Am. J. Surg. 2006, 191, 94 99. [11] SPIRO J. D., SPIRO R. H., SHAH J. P., SESSIONS R. B., STRONG E.W.: Critical assessment of supraomohyoid neck dissection. Am. J. Surg. 1988, 156, 286 289. [12] HAO.S. P., TSANG N. M.: The role of supraomohyoid neck dissection in patients of oral cavity carcinoma. Oral Oncol. 2002, 38, 309 312. [13] YOUSSEF E., CHUBA P., SALIB N., YOO G. H., PENAGARÍCANO J., EZZAT W., AREF A. Pathological distribution of positive lymph nodes in patients with clinically and radiologically N0 oropharyngeal carcinoma: implications for IMRT treatment planning. Cancer J. 2005, 11, 412 416. [14] ROBBINS K.T., CLAYMAN G., LEVINE P.A., MEDINA J., SESSIONS R., SHAHA A.: American Head and Neck Society; American Academy of Otolaryngology Head and Neck Surgery. Neck dissection classification update: revisions proposed by the American Head and Neck Society and the American Academy of Otolaryngology Head and Neck Surgery. Arch. Otolaryngol. Head Neck Surg. 2002, 128, 751 758. [15] VARTANIAN J. G., PONTES E., AGRA I. M., CAMPOS O. D., GONÇALVES FILHO J., CARVALHO A. L., KOWALSKI L. P.: Distribution of metastatic lymph nodes in oropharyngeal carcinoma and its implications for the elective treatment of the neck. Arch. Otolaryngol. Head Neck Surg. 2003, 129, 729 732. [16] KHAFIF A., LOPEZ GARZA J. R., MEDINA J. E.: Is dissection of level IV necessary in patients with T1 T3 N0 tongue cancer? Laryngoscope 2001, 111, 1088 1090. [17] MAJOUFRE C., FAUCHER A., LAROCHE C., DE BONFILS C., SIBERCHICOT F., RENAUD SALIS J. L.: Supraomohyoid neck dissection in cancer of the oral cavity. Am. J. Surg. 1999, 178, 73 77. [18] KOWALSKI L. P., CARVALHO A. L.: Feasibility of supraomohyoid neck dissection in N1 and N2a oral cancer patients. Head Neck 2002, 24, 921 924. [19] DIAS F. L., KLIGERMAN J., MATOS DE SÁ G., ARCURI R. A., FREITAS E. Q., FARIAS T.: Elective neck dissection ver sus observation in stage I squamous cell carcinomas of the tongue and floor of the mouth. Otolaryngol. Head Neck Surg. 2001, 125, 23 29. [20] CLAYMAN G. L., FRANK D. K.: Selective neck dissection of anatomically appropriate levels is as efficacious as modified radical neck dissection for elective treatment of the clinically negatice neck in patients with squamous cell carcinoma of the upper respiratory and digestive tracts. Arch. Otolaryngol. Head Neck Surg. 1998, 124, 348 352. [21] Brazilian Head and Neck Cancer Study Group: Results of a prospective trial on elective modified radical classi cal versus supraomohyoid neck dissection in the management of oral squamous carcinoma. Am. J. Surg. 1998, 176, 422 427. [22] KOWALSKI L. P., BAGIETTO R., LARA J. R., SANTOS R. L., SILVA J. F. JR, MAGRIN J.: Prognostic significance of the distribution of neck node metastasis from oral carcinoma. Head Neck 2000, 22, 207 214. [23] DUVVURI U., SIMENTAL A. A. JR, D ANGELO G., JOHNSON J. T., FERRIS R. L., GOODING W., MYERS E. N.: Elective neck dissection and survival in patients with squamous cell carcinoma of the oral cavity and oropharynx. Laryngoscope 2004, 114, 2228 2234. Address for correspondence: Marcin Kos Department of Maxillofacial Surgery Klinikum Minden Friedrichstrasse 17 32 427 Minden Germany Tel.: +49 571 790 53751 Fax: +49 571 801 3721 E mail: mkos@poczta.onet.pl Received: 10.04.2008 Revised: 28.04.2008 Accepted: 28.04.2008 Praca wpłynęła do Redakcji: 10.04.2008 r. Po recenzji: 28.04.2008 r. Zaakceptowano do druku: 28.04.2008 r.