Autofluorescence Endoscopy in Diagnosis of Laryngeal Lesions

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1 original papers Adv Clin Exp Med 2010, 19, 4, ISSN X Copyright by Wroclaw Medical University Maciej D. Zatoński 1, Tomasz Kręcicki 2, Agnieszka Jabłonka-Strom 1, Agnieszka Zatońska 3, Agata Górecka 4, Marek Bochnia 1 Autofluorescence Endoscopy in Diagnosis of Laryngeal Lesions Endoskopia autofluorescencyjna w diagnostyce zmian nabłonkowych krtani 1 Department of Otolaryngology, Faculty of Dentistry, Wroclaw Medical University, Poland 2 Department of Otolaryngology, Head and Neck Surgery, Wroclaw Medical University, Poland 3 Department of Otolaryngology, District Railway Hospital, Wroclaw, Poland 4 Department of Otolaryngology, University Hospital (ASK), Wroclaw, Poland Abstract Background. One of the most important problems in head and neck oncology is early diagnosis of laryngeal cancer. Despite the introduction of new therapeutic methods and improvement of surgical techniques, patients 5-year survival rate still depends primarily on the stage of the disease at the moment of introduction of appropriate treatment. Objectives. The goal of this study was to assess the efficacy of autofluorescence endoscopy () in diagnosis of laryngeal lesions. examinations were carried out on out-patient basis, without general anesthesia and without using any photosensitizing agents (topical or systemic). Sensitivity and specificity of alone, as well as combined with classic white-light endoscopy, were calculated. Material and Methods. 129 patients (30 women and 99 men) at the age between with various laryngeal pathologies entered the study. Patients did not receive any photosensitizing agents. No tissue staining was used. Occasionally, the patients received local 10 Xylocaine anesthesia before the examination. All examinations were performed using modified laryngeal endoscopic setup. All patients underwent classical white-light endoscopy followed by examination. Sites of possible pathologies were noted for further biopsy. The results obtained during white-light endoscopy and were then compared to histopathological findings. Sensitivity and specificity were calculated. Results. Suspected malignant lesions were confirmed in 63 out of 72 cases when using white-light endoscopy, and in 71 out of 72 during (p = ). In precancerous lesions, 9 out of 19 were identified during white-light endoscopy, while allowed to properly identify 16 out of 19 precancerous lesions (p = ). In all lesions, histologically classified as benign, the authors received 18 false positive results (white-light endoscopy) and 7 false positive results with (p = ). Overall sensitivity of was 95.6 and specificity was For whitelight endoscopy the results were 79.1 and 52.6 respectively. Combined specificity of both methods was Conclusions. is an effective, supplementary method of diagnosing pathologies of the glottic as well as supraglottic region of the larynx, that can be used in routine out-patient care. is completely safe and has a very high sensitivity in detecting invasive cancer as well as early precancerous lesions (starting from LIN II). It allows to precisely visualize the extensions of the lesion and can be used to diagnose changes in supraglottic region. can also be used in monitoring patients after treatment and in early detection of possible recurrence (Adv Clin Exp Med 2010, 19, 4, ). Key words: laryngeal cancer, autofluorescence, early diagnosis. Streszczenie Wprowadzenie. Diagnostyka i leczenie raka krtani jest dziś jednym z największych wyzwań w onkologii głowy i szyi. Mimo rozwoju nowych metod terapeutycznych i wprowadzeniu nowoczesnych technik chirurgicznych, w dalszym ciągu 5-letnie przeżycia w przypadku raka krtani zależą prawie wyłącznie od stanu zaawansowania choroby w chwili rozpoczęcia leczenia.

2 462 M. Zatoński et al. Cel pracy. Ocena skuteczności endoskopii autofluorescencyjnej () w diagnostyce zmian nabłonkowych w krtani. Opisana metoda pozwala na wykonywanie badania w trybie ambulatoryjnym, bez ogólnego znieczulenia i bez konieczności stosowania środków fotouczulających (zarówno miejscowo, jak i ogólnie). Obliczono czułość i specyficzność badania z wykorzystaniem endoskopii autofluorescencyjnej jako samodzielnej metody diagnostycznej oraz w połączeniu z klasycznym badaniem endoskopowym w białym świetle. Materiał i metody. Badaniem objęto 129 pacjentów (30 kobiet i 99 mężczyzn) w wieku lat, którzy zgłosili się do pracowni endoskopowej Kliniki Otolaryngologii. Nie podawano żadnych środków fotouczulających ani barwników tkankowych. Sporadycznie stosowano znieczulenie miejscowe 10 roztworem Xylocainy przed rozpoczęciem badania. wykonywano z użyciem zmodyfikowanego zestawu do endoskopii krtani zaraz po klasycznym badaniu endoskopowym. Z podejrzanych obszarów krtani pobierano następnie wycinki do badania histologicznego. Wyniki otrzymane w czasie badań endoskopowych i były porównywane do wyników badań histopatologicznych. Wyniki. Podejrzenie zmian złośliwych potwierdziło się w 63 z 72 przypadków podczas klasycznej endoskopii i w 71 z 72 przypadków w badaniu (p = 0,0087). W przypadku zmian przedrakowych podczas badania w świetle białym zidentyfikowano 9 z 19 przypadków, a z użyciem 16 z 19 (p = 0,0166). W zmianach zakwalifikowanych histologicznie jako łagodne otrzymano 18 fałszywie dodatnich wyników (endoskopia klasyczna) oraz 7 po badaniu (p = 0,0072). Czułość wyniosła 95,6, a specyficzność 79,1. Dla klasycznej endoskopii wyniki wynosiły odpowiednio 81,6 oraz 52,6. Łączna czułość obu metod diagnostycznych (endoskopia w świetle białym + ) zastosowanych łącznie wyniosła 96,7. Wnioski. jest skuteczną uzupełniającą metodą diagnostyczną, pozwalającą wcześnie rozpoznawać zmiany w krtani (zarówno w głośni, jak i nadgłośni). Może być używana podczas rutynowego badania w trybie ambulatoryjnym. jest całkowicie bezpieczna dla pacjenta. Charakteryzuje się bardzo wysoką czułością w rozpoznawaniu zmian nowotworowych i przednowotworowych (już od LIN II). Pozwala na precyzyjną ocenę rozległości zmian i może być używana do wczesnej diagnostyki zmian w nadgłośni. może być także używana w monitorowaniu pacjentów po leczeniu oraz do wczesnego wykrywania ewentualnej wznowy (Adv Clin Exp Med 2010, 19, 4, ). Słowa kluczowe: rak krtani, wczesna diagnostyka, autofluorescencja. Cancer of the larynx makes 2 4 of all malignant tumors and is the 6 th most common cause of death out of all deaths caused by malignant tumors in men in Poland [1]. Prognoses and survival rates depend strongly on the tumors advancement (stage) at the introduction of appropriate therapy. In Poland only 26 of all malignant laryngeal tumors is at early stages of development at the time of initial diagnosis. Therefore early diagnostics and treatment of laryngeal cancer is one of the most important challenges in the head and neck oncology. Lesions that originate in the glottic region usually present with hoarseness, which is often noticed by patients, their families or their physicians. In other cases, often the first noticeable sign of the neoplastic process is enlargement of regional lymph nodes. Early diagnosis of laryngeal tumors allows to introduce the treatment at early stages of the disease and increases both the chances of survival and the quality of life of patients treated from laryngeal cancer. Most of described in the literature autofluorescence diagnostic procedures requires general anesthesia or photosensitizing agents. The technique described below lacks the above mentioned limitations. It allows to use autofluorescence endoscopy () during routine endoscopic examination of the larynx. The goal of this study was to assess: a) the efficiency of in diagnosing laryngeal pathologies in comparison to classic white-light endoscopy; b) specificity and sensitivity of as a standalone method and combined with classic endoscopic examination; c) usefulness of in treatment monitoring. The results were compared to histopathological findings. Material and Methods Material included 129 patients (30 women and 99 men). The mean age of patients was 58.6 years (22 to 89 years old). Ninety one patients with suspected malignant lesions and 38 patients with benign changes (Reinke s Oedema, papillomas, polyps, vocal nodules, granulomas, chronic hypertrophic laryngitis). The authors did not use general anesthesia. Sporadically the patients were sprayed with 10 Xylocaine solution. Patients did not receive any photosensitizing agents, neither topically nor systemic. No tissue staining was used. The examinations were performed using modified STORZ set-up for laryngeal endoscopy. It consisted of white-light source (xenon) with possibility to switch to blue-light during the examination, optic fiber and rigid laryngeal 70 o endoscope. The endoscope was connected to high-sensitivity CCD camera (Telecam PDD Storz). The set was equipped with system of filters eliminating reflected excitation light (blue). The filters were able to pass the light waves around 400 nm and over 450 nm. The pictures from the camera obtained during white and blue light examinations were recorded and stored on a PC-class computer for further assessment. The examination started with classic white light endoscopy. The landmarks suspected of neoplastic

3 AF Endoscopy in Laryngeal Pathologies 463 changes were noted for further biopsy. When necessary stroboscopic examination was performed. was performed right after white-light examination. The picture from the camera was observed in real-time and stored on a PC computer. All the patients suspected for malignant changes underwent standard biopsy. The material was sent for histopathological examination. The spots for biopsy were identified during previously performed white light and blue light examinations. Further treatment of the patients was dependent on histopathological findings. Material obtained by removing benign lesions underwent histopathological evaluation post-operatively. Digitally stored white and blue light examinations were then compared to the histopathological findings. The endoscopic findings were classified as positive, negative, false positive and false negative to assess sensitivity and specificity of and white-light endoscopy. These results were later statistically tested with chi-square test (Statistics Calculator 3, StatPac Inc.). Level of p < 0.05 was considered to indicate significant difference between groups. Results The histopathological findings performed in 129 patients included 72 cases of invasive cancer, 19 pre-cancerous states and 38 benign pathologies. The detailed diagnoses are presented in Table 1. Malignancies that were initially suspected in classic white-light videoendoscopy were histopathologically confirmed in 63 out of 72 cases, while in in 71 out of 72. Nine false negative results in white light examination and only 1 in (Table 2). This difference was statistically significant (p = ). allowed to properly identify 16 out of 19 precancerous lesions confirmed in histopathological examinations, while white light videoendoscopy allowed for proper identification of 9 out of 19 cases. The false negative results were 3 and Table 1. Histological findings in the analyzed samples taken from 129 patients Tabela 1. Rozpoznania histopatologiczne w materiale pobranym od 129 pacjentów Histopathological finding (Rozpoznanie histopatologiczne) Number of diagnoses (Liczba rozpoznań) Carcinoma planoepitheliale keratodes 52 Dysplasia (LIN I, II, III) 29 Carcinoma planoepitheliale akeratodes 14 Leucoplakia (without dysplasia) 13 Chronic hypertrophic laryngitis 9 Reinke s oedema 8 Carcinoma keratoblasticum 5 Laryngeal polyposis 4 Pachydermia 4 Carcinoma in-situ 4 Laryngeal papilloma 3 Vocal nodules 2 Laryngeal tuberculosis 1 Total (Suma) 148 * The total number in the table exceeds 129 (the number of the patients), because in some cases more than one pathology was diagnosed in the same patient (e.g. dysplasia and invasive cancer, dysplasia and leucoplakia, leucoplakia and chronic laryngitis, etc). * Liczba rozpoznań przekracza 129 (liczbę pacjentów), ponieważ w niektórych przypadkach rozpoznawano więcej niż jedną patologię u tego samego pacjenta (np. dysplazja i rak inwazyjny, dysplazja i leukoplakia, leukoplakia i przewlekły stan zapalny).

4 464 M. Zatoński et al. Table 2. Number of positive and false negative results (laryngeal cancer) during white-light and examinations Tabela 2. Liczba dodatnich i fałszywie ujemnych wyników (rak krtani) dla i klasycznej endoskopii w świetle białym Positive (+) (Dodatni) (+) False negative (f-) (Fałszywie ujemny) (f-) Table 3. Number of positive and false negative results (precancerous lesions) during white-light and examinations Tabela 3. Liczba wyników dodatnich i fałszywie ujemnych (stany przedrakowe) dla i endoskopii w świetle białym Positive (+) (Dodatni) (+) False negative (f-) (Fałszywie ujemny) (f-) Laryngeal carcinoma (n = 72) (Rak krtani) (n = 72) * Autofluorescence Endoscopy. Laryngeal intraepithelial neoplasia (LIN) (n=19) (Neoplazja śródnabłonkowa krtani LIN) (n=19) * Autofluorescence Endoscopy. ** LIN Laryngeal Intraepithelial Neoplasia. ** LIN neoplazja śródnabłonkowa krtani. white light examination white light examination 10 respectively (Table 3). This difference also showed to be statistically significant (p = , Pearson). Out of all 91 patients with precancerous or cancerous pathologies allowed to properly identify 87 cases, while videoendoscopy 72 out of 91 (Table 4). The most significant difference was observed for early pathologies (p = ). Table 4. Number of positive and false negative results (LINs and laryngeal carcinomas) during white-light and examinations Tabela 4. Liczba dodatnich i fałszywie ujemnych wyników (LIN i raki krtani) dla i klasycznej endoskopii w świetle białym Positive (+) (Dodatni) (+) False negative (f-) (Fałszywie ujemny) (f-) LIN and Laryngeal Cancer (n = 91) (LIN i rak krtani) (n = 91) * autofluorescence endoscopy. ** LIN laryngeal intraepithelial neoplasia. ** LIN neoplazja śródnabłonkowa krtani. white light examinations Table 5. Number of true negative and false positive results (benign changes) obtained during white-light and examinations Tabela 5. Liczba ujemnych i fałszywie dodatnich wyników (zmiany łagodne) dla I klasycznej endoskopii w świetle białym Negative ( ) (Ujemny) ( ) False positive (f+) (Fałszywie dodatni) (f+) Benign changes (n = 38) (Zmiany łagodne) (n=38) * autofluorescence endoscopy. white light examinations In the cases histologically classified as benign, white light examination allowed to properly identify 20 out 38 cases (18 false positive results). allowed to properly identify 31 out of 38 cases (7 false positive results) (p = ). Results are presented in Table 5. The above presented results were used to calculate sensitivity (Table 6) and specificity (Table 7) of and white light examination in diagnosing malignant and premalignant lesions.

5 AF Endoscopy in Laryngeal Pathologies 465 Table 6. Comparison of sensitivity of and white-light endoscopy as a stand-alone and combined method of diagnosing laryngeal neoplasms Tabela 6. Porównanie czułości i endoskopii w świetle białym jako samodzielnych metod diagnostycznych oraz zastosowanych łącznie w diagnostyce zmian nowotworowych i przednowotworowych w krtani Sensitivity (Czułość) white-light endoscopy + white-light endoscopy Cancer (n = 72) (Rak krtani) (n = 72) LIN (n = 19) (LIN) (n = 19) LIN + cancer (n = 91) (LIN + raki krtani) (n = 91) * Autofluorescence Endoscopy. ** LIN Laryngeal Intraepithelial Neoplasia. ** LIN neoplazja śródnabłonkowa krtani. Table 7. Specificity of and white-light endoscopy Tabela 7. Specyficzność i endoskopii w świetle białym Benign lesions (Zmiany łagodne) (n = 38) Discussion Specificity (Specyficzność) * Autofluorescence Endoscopy. white-light endoscopy Laryngeal cancer is the most common cancer of upper respiratory tract in men [2, 3]. Prolonged exposition to external carcinogens (such as tobacco smoke or alcohol abuse) causes damage to large areas of upper airways mucosa, resulting in development of cancerous changes. In the recent years the authors have observed intensive development of methods of treatment of laryngeal cancer. Beside numerous selective and preserving surgical procedures, effective methods of radiotherapy and chemoradiotherapy were introduced to offer the patients treatment options that are more efficient, more effective, less traumatizing and provide better quality of life. Despite this progress in the treatment, 5-year survival rate in the past 30 years did not change and approximates at about 50 for all stages of the disease [2, 4, 5]. Two major factors contribute to this fact: delayed diagnosis and relatively high percentage of developing a second primary focus of the disease after treatment [6, 7]. Many head and neck carcinomas are preceded by so-called precancerous lesions (histologically defined as laryngeal intraepithelial neoplasia LIN, or previously dysplasia). Clinically, they are possible to detect only when accompanied by easy to spot pathologies (such as leucoplakia or erythroplakia). Diagnosis and treatment of laryngeal cancer presents a significant health problem, not only in Poland, but also worldwide. Non-invasive diagnostic tool that would allow to detect dysplastic changes would also allow to prevent or early diagnose laryngeal cancer. Early diagnosis enables to early introduce appropriate therapy and improves the chance of patients survival. Many diagnostic techniques described in available literature are based on using 5-aminolevulinic acid (5-ALA) to induce fluorescence of endogenic protoporphyrin IX (PpIX). 5-ALA was usually administered intravenously 1 4 hours prior the examination. The most important drawback of this method are the side effects of photosensitizers. Doses as low as 30 mg/kg of ALA can cause nausea, vomiting, elevation of liver enzymes and increase skin sensitivity to sunlight. Such side effects do not present a problem during photodynamic therapy (PDD) but cannot be accepted during routine examinations [8]. 5-ALA can also be administered topically, right before the blue light examination [9 12]. Cancerous tissues tend to accumulate PpIX. Achieved results are characterized

6 466 M. Zatoński et al. by strong, easy to spot, red fluorescence of cancerous tissues. In the literature, topical administration of 5-ALA was done by inhaling 30 mg of 5-ALA in 5 ml 0.9 NaCl solution 1 2 hours before the microlaryngoscopy. Results allowed to assess sensitivity and specificity of this technique (95 and 80 respectively). In the years several reports on using Light-induced Fluorescence (LIF) for diagnosing laryngeal pathologies were published. Baletic et al. used complete autofluorescence endoscopy system (designed to diagnose lower airways) to diagnose laryngeal epithelium. Patients were examined with flexible bronchoscope in local anesthesia. The authors assessed sensitivity of S system to be 92.1 (and 73.7 in white light examination) [13]. Kulapaditharom and Boonkitticharoen showed that sensitivity of LIF system in diagnosing laryngeal carcinomas was 100 with 87.5 specificity (in a group of 25 patients) [14]. Other researchers achieved similar results [15]. The main problems with introducing above mentioned systems based on selective spectrum enhancers or spectrometric analysis to the routine examination are high costs and necessity to use general anesthesia. The investigated tissue needs to be examined from a very close distance (about 1 cm) for example by introducing an endoscope through the Kleinsasser s set. Using flexible bronchoscopes requires at least topical anesthesia (the optics need to be close to the vocal cords) and significant patient s cooperation. The technique described in this paper lacks the above mentioned limitations. It does not require general anesthesia. There is no need to use any photosensitizing agents. It allows to examine the larynx from much greater distance (with rigid laryngoscope). The recorded image is of far greater quality then image acquired from flexible optics. Available laryngeal endoscopic systems can be easily adopted to perform. The examination can be quickly performed and repeated as often as necessary on out-patient basis. The main drawback is caused by the limited amount of light available for the CCD detector. The image is too dark to be viewed by a naked eye (directly through endoscope optics). Proper exposure requires thus longer exposition time. Practically it means that the pictures is refreshed no more than 4 times per second (instead of normal 25/sec rate). In order to achieve a sharp, clear picture of the larynx, the endoscope has to be held firmly without any movement for this time. This requires patient s cooperation, although not as much as during bronchoscopy. For the same reason a CCD camera and a computer with monitor are required to perform the examination. Results achieved in own study rate the sensitivity of at 95.6 and its specificity at 81.6 and are comparable to results achieved by other authors [15 18]. Technique described in this study is simpler to apply. The examination itself is also easier to bear for the patient and can be performed completely on out-patient basis. This allows the present auhors to question the need of using 5-ALA in diagnosing laryngeal cancer. The big advantage of is its high sensitivity in detecting early stages of neoplastic transformation. In own material false negative results were almost exclusively found in early dysplastic lesions (LIN I and II). However a strong, green fluorescence can be observed in cases of severe keratosis on the cancer s surface, it is usually seen in advanced tumors with accompanying lack of fluorescence in the immediate area of keratosis. Such picture does not present any diagnostic difficulties. In the examined material there was not any case that would lead to improper diagnosis, although it is (theoretically) possible that the keratosis may completely cover the neoplastic process (potential possibility of false negative results). In own study the authors have found more false-positive than false-negative results. The falsepositives were found mainly in laryngeal papillomas and chronic hypertrophic laryngitis, one falsepositive case of leucoplakia without accompanying dysplasia, one vocal cord nodule and one case or Reinke s oedema. There was also one patient suspected of laryngeal cancer, with typical lack of green fluorescence which was histopathologically diagnosed as laryngeal tuberculosis. Reassuming in clinical practice false-positive results present lesser problem than false-negative ones, because the consequences of false-negative results are far more dangerous for patients. High sensitivity allows for precise and early diagnosis, that in case of laryngeal cancers decides of the patient s survival and quality of life after treatment. Early detection is the key to successful treatment. allows to detect pathologies that are otherwise clinically silent. In the examined material most tumors were in late stages of advancement (stage III and IV). In those cases, is of a little strictly diagnostic use, since due to the size of the tumor, clinical diagnosis is relatively easy. However allows for much more accurate assessment of tumor s size and its borders; allows to precisely mark spots for biopsy, and makes early detection of possible recurrence much easier. In cases of very early detected pathologies, such as LIN I or II, it allows to decide whether to schedule the patient for biopsy or continue observation.

7 AF Endoscopy in Laryngeal Pathologies 467 Blue-light examination seems to be an excellent addition to the classic white-light endoscopy of the larynx. Combining these two methods allows to significantly increase chances of proper diagnosis of early laryngeal neoplasia. Popularization of this method may contribute to increased survival and better results of treatment of patients with laryngeal cancer. The authors concluded that autofluorescence endoscopy is an efficient, safe and easy to perform complementary diagnostic tool, that may be regularly used in out-patient clinics during routine ENT examination of glottic and supraglottic region of the larynx. is characterized by very high sensitivity and high specificity in diagnosing laryngeal cancer and pre-cancerous lesions, starting from mid-grade dysplasia (LIN II). allows for precise biopsy and accurate assessment of the spread of the lesion. References [1] Didkowska J, Wojciechowska U, Tarkowski W et al.: Nowotwory złośliwe w Polsce w 2000 roku. Centrum Onkologii Instytut im. M. Skłodowskiej-Curie, Warszawa [2] Kręcicki T, Zalesska-Kręcicka M, Zatoński M, Zatoński T, Frączek M: Diagnostyka autofluorescencyjna w przypadku zmian nabłonkowych krtani. Otorynolaryngologia Przegl Klin 2005, 4 supl.1, s [3] Ferlay J, Bray F, Pisani P et al.: GLOBOCAN 2002: Cancer incidence, mortality and prevalence worldwide. IARC CancerBase ver. 2.0, IARC Press, Lyon 2005, 4. [4] Hirsch F et al.: Fluorescence vs white-light endoscopy for detection of preneoplastic lesions: a randomized study. Kennedy TC JCNI 2001, 93, [5] Parker S, Tong T, Bolden S et al.: Cancer Statistics, CA Cancer J Clin 1996, 65, 5. [6] Dhingra J, Zhang X, Mcmillan K et al.: Diagnosis of Head and Neck Precancerous Lesions in an Animal Model Using Fluorescence Spectroscopy. Laryngoscope 1998, 108, [7] Day G, Blot W: Secondary Primary Tumors in Patients with Oral Cancer. Cancer 1992, 70, [8] Haringsma J, Tytgat G: The Value of Fluorescence Techniques in GI Endoscopy: Better than the Endoscopist s Eye? The European Experience. Endoscopy 1998, 30, [9] Leunig A, Betz CS, Heinrich P, Janda P, Baumgartner R: Fluorescence staining of oral and laryngeal cancer after application of 5-aminolevulinic acid. Laryngorhinootologie 2002 Nov, 81(11), [10] Leunig A, Mehlmann M, Betz C et al.: Fluorescence staining of oral cancer using topical application of 5-ALA: fluorescence microscopy studies. J Photochem Photobiol 2001, 60, [11] Piotrowski WJ, Marczak J, Nawrocka A, Antczak A, Górski P: Inhalations of 5-ALA in photodynamic diagnosis of bronchial cancer. Monaldi Arch Chest Dis 2004, 61(2), [12] Csanady M, Kiss JG, Ivan L, Jori J, Czigner J: ALA (5-aminolevulinic acid)-induced protoporphyrin IX fluorescence in the endoscopic diagnostic and control of pharyngo-laryngeal cancer. Eur Arch Otorhinolaryngol 2004, 261(5), [13] Baletic N, Petrovic Z, Pendjer I et al.: Autofluorescent diagnosis in laryngeal pathology. Eur Arch Otorhinolaryngol 2004, 261, [14] Kulapaditharom B, Boonkitticharoen V: Laser-induced fluorescencje imaging in localization of head and neck cancers. Ann Otol Rhinol Laryngol 1998, 107, 3 7. [15] Malzahn K, Dreyer T, Glanz H, Arens C: Autofluorescence Endoscopy in the Diagnosis of Early Laryngeal Cancer and Its Precursor Lesions. Laryngoscope 2002, 112, [16] Zargi M, Fajdiga I, Smid L: Autofluorescence imaging in the diagnosis of laryngeal cancer. Eur Arch Otorhinolaryngol 2000, 257, [17] Baletic N, Petrovic Z, Pendjer I et al.: Autofluorescent diagnosis in laryngeal pathology. Eur Arch Otorhinolaryngol 2004, 261, [18] Kulapaditharom B, Boonkitticharoen V: Laser-induced fluorescencje imaging in localization of head and neck cancers. Ann Otol Rhinol Laryngol 1998, 107, 3. Address for correspondence: Maciej Dariusz Zatoński Department of Otolaryngology, Faculty of Dentistry Wroclaw Medical University Borowska Wrocław Poland Tel.: public.mz@gmail.com Conflict of interest: None declared Received: Revised: Accepted: