Premalignancies and CO2 laser surgery

Surgical Management of Premalignant Lesions of the Oral Cavity with the CO2 Laser

Antonio L.B. PINHEIRO1 John W. FRAME2 1Departamento de Prótese e Cirurgia Buco-Facial, Universidade Federal de Pernambuco, Recife, PE, Brasil 2Oral Surgery and Oral Medicine Unit, School of Dentistry, University of Birmingham, Birmingham, UK

Braz Dent J (1996) 7(2): 103-108 ISSN 0103-6440

The management of patients with premalignant and malignant lesions of the oral cavity can present problems. The potentially invasive nature of premalignant lesions together with their large extent influences the treatment. The common modalities of treatment of these lesions are surgical excision, cryotherapy, electrosurgery and radiotherapy. Recently, CO2 laser surgery has become available. Less pain, little bleeding, minimal post-operative edema, reduced risk of infection, and low recurrence rates were advantages observed following CO2 laser surgery in the mouth when compared to other modalities of treatment. Healing following CO2 laser surgery progressed well with little post-operative scarring and re-epithelialization was complete after 4-6 weeks. The newly formed epithelium appeared normal and was soft on palpation.

Key Words: instrumentation, leukoplakia, SCC, laser surgery.

Introduction

A precancerous lesion is a “ morphologically altered tissue in which cancer is more likely to occur than in its apparently normal counterpart” and in which its “generalized state is associated with significantly increased risk of cancer” (WHO, 1972). In the mouth there are two main precancerous lesions: leukoplakia and erythroplakia. Leukoplakia is defined as a white patch or plaque that cannot be characterized clinically or pathologically as any other disease (WHO, 1978). This definition has no histological connotation. Cigarette smoking and alcohol intake have been identified as important etiological risk factors for mouth cancers in the developed world. In developing countries, betel and tobacco chewing are also important risk factors. There is also evidence that mouth cancer risk increases with the use of oral snuff and dietary factors may also be of importance in the etiology of this disease. There is sufficient evidence that tobacco is carcinogenic to humans and that the occurrence of malignant tumors of the upper aerodigestive tract is causally related to the smoking of different forms of tobacco (IARC, 1986). Even marijuana smoke has been associated with upper aerodigestive cancers in a relatively young series of patients (Peters and Morgan, 1990). Although alcohol is not a chemical carcinogen which produces cancer in experimental animals, there is overwhelming evidence that consumption of alcohol increases the risk of cancer. There is evidence for a role of alcohol consumption in the etiology of mouth cancers which appears to be independent of cigarette smoking (IARC, 1989). Franceschi et al. (1990) found that the risk is directly and proportionally related to the number of drinks taken. Although pan-tobacco chewing is also a major risk factor for cancer, especially cancers of the buccal and labial mucosa, it is not common among the Brazilian population. The incidence of premalignant and malignant lesions throughout the world varies widely. Males are affected more commonly than females at the sites under consideration, with the greatest difference between the sexes being observed most often in relation to cancer of the lip (Smith, 1989). It is well known that leukoplakia is more common in males, with ratios up to 5.29:1 (Axéll, 1987). These variations are at least partly attributable to differences in sampling methods and, usually, the M:F ratio in leukoplakia seems to be between 2:1 and 3:19 (Kramer et al., 1978). However, a recent report (CRC, 1990) showed that the sex ratio has altered, with the male rates falling proportionally more than female rates. The decline in the rates in the UK may be a result of the decrease in pipe smoking amongst males and an increase in cigarrete/alcohol use by females. There is still controversy about the risks of malignant transformation of oral premalignant lesions. The frequency of carcinomatous changes in oral leukoplakia has been found to vary between 1.4 to 6%. However, Kramer et al. (1978) reported values of 25% for malignant transformation in leukoplakia in the floor of the mouth and ventral surface of the tongue. The clinical type and malignant transformation of oral leukoplakia seems to be correlated (Bánóczy, 1982). Speckled leukoplakia has a greater tendency for malignant transformation than the more common homogeneous type. Most authors agree that speckled leukoplakia is more often associated with epithelial dysplasia than the homogeneous type. Frame et al. (1984) discussed the incidence of malignant transformation in leukoplakia and reported transformation rates up to 6%, and that patients with this condition have a likelihood of up to 100% of developing cancer when compared to the rest of the population. Various sites of the mouth where premalignant lesions may occur include the vermilion border, labial mucosa, labial commissures, buccal mucosa and floor of the mouth. Bánóczy (1982) suggested that the most common site for leukoplakia is the commissure (42%), followed by the buccal mucosa (22%) in males, and the buccal mucosa (40%) and commissures (19.2%) in females. It is well accepted that certain sites carry a higher risk of malignant transformation. There is a general consensus that surgical excision of oral leukoplakia is the best treatment for this lesion. Among the surgical treatments, CO2 laser surgery is the technique of choice (Chiesa et al., 1993).

Patients and Methods

Fifty-seven patients with biopsy-proven oral premalignant and malignant lesions were treated with the CO2 laser during a period of 6 years at the Departments of Oral Surgery and ENT Surgery at the Queen Elizabeth Medical Center in Birmingham, England. There were other patients treated during the same period, but their medical records were not available. The presence of any etiologic factor was identified and then eliminated where possible before treatment was undertaken. Routine follow-up was carried out on a regular basis. General anesthesia was generally used since the lesions frequently involved widespread areas of the mouth. With local anesthesia it was sometimes difficult for the patient to control unintentional movements of the soft tissues, especially the tongue. During surgery, the endotracheal anesthetic tube was protected with metal tape, and a moist gauze pack placed in the oro-pharynx around the tube. For additional protection, the surrounding area was covered with moist gauze and the eyes protected with pads and moistened gauze. Prophylactic antibiotics were given to 14 patients. The Sharplan 791 surgical laser was used to perform the surgery, and was attached either to a Zeiss operating microscope or to a handpiece. When attached to the microscope, there was good visualization of the operative field with precise delivery of the laser beam to the surgical site. The CO2 laser was used at a power output of 5 to 15 Watts on pulsed or continuous mode. For premalignant lesions, the limits were first marked with the laser beam and then vaporization or excision was performed. Vaporization of the surface mucosa was used in less accessible areas of the mouth. A shallow wound was produced and healed well. Excision of the lesion with some of the underlying tissue created a slightly deeper wound, providing material for further histological examination. The laser was then defocused and the wound surface vaporized as a means of hemostasis and elimination of any remnants of the lesion (Frame et al., 1984). For the excision of malignant lesions, standard oncological principles were observed, including adequate margins and the delivery of an intact specimen. Excision was used in all cases of malignant disease. These were a selected group of malignant lesions: they were readily accessible, in the anterior region of the mouth, and amenable to CO2 laser excision. Healing following laser surgery generally progressed well. Re-epithelialization was complete after 4-6 weeks and the newly formed epithelium appeared healthy in most patients. There was little post-operative scarring and tissues were soft on palpation. In some elderly patients, the newly formed epithelium appeared rather thin and atrophic.

Results

Twenty-two female and thirty-five male patients, aged between 37 and 86 years (mean 62.7 years) were evaluated. The diagnosis of the 57 lesions treated with the CO2 laser were: mucoepidermoid carcinoma (MEC), squamous cell carcinoma (SCC), hyperkeratosis (HP), parakeratosis (P), verrucous carcinoma (VC), leukoplakia (LK), sublingual keratosis (SLK), and carcinoma in situ (CS). The most common site of the premalignant lesions was the floor of the mouth\ventral tongue (9); other parts of the tongue (10) were the most frequent site of malignant lesion (Figure 1). Five of thirty-one patients in the malignant group developed recurrences of the lesion. Three showed histologic evidence of field change. One patient developed an antral tumor two years after the removal of a SCC of the palate. Four patients died of unrelated causes during the follow-up period of 8 months. Seventeen patients are well and their disease controlled. Two of twenty-six patients in the premalignant group showed recurrences of the lesion within 3 to 18 months. One patient developed a new lesion on the opposite cheek 60 months after the removal of a lesion in the other cheek. One patient died 6 months after surgery of unrelated disease. Twenty-two patients with premalignant lesions were cured and their disease is now under control. Four patients developed infection of the wound within the first five days after surgery. In two cases, the affected area was the tongue, and in the other two cases, lower alveolus. One patient developed gross edema following the removal of a SCC of the tongue, another patient had post-operative hemorrhage following the resection of SCC of the tongue. Another patient developed temporary numbness of the tongue following excision of a SCC, and another patient developed trismus after removal of an extensive hyperkeratotic lesion of the lower alveolus. Pain was experienced by a few patients and was controlled by paracetamol or compound analgesic in low-dosage (Paramol or Co-proxamol). Moderate or severe pain was controlled with a mixed opium alkaloid (Papaveratum) or opioid analgesics (Pethidine, Dihydrocodeine, or Codeine phosphate). Dexamethazone was used in a patient who had gross edema of the tongue. The length of stay in the hospital varied from 1 to 5 days (mean, 2 days). Two patients stayed longer than five days when major cancer resections were performed. However, the longer time in the hospital was not related to the laser surgery procedure, but to the general condition of the patient before surgery. The follow-up period varied from 19 days to 60 months (mean 11.3 months).

Discussion

Although males are considered more at risk of developing premalignant and malignant lesions in the oral cavity, in this series there was no evidence of differences between males and females with respect to diagnosis, site and age. The most frequently affected area was the floor of the mouth and tongue, in agreement with previous research (Flynn et al., 1988; Hogewind and van der Waal, 1988). However Bánóczy (1982) report the commissures as the most common site. To treat soft-tissue pathology in the mouth with the CO2 laser, either a handpiece or an operating microscope can be used, and the laser beam can be focused as a cutting tool or defocused to vaporize tissue. It is extremely important to perform histologic examination before vaporizing a lesion to establish the diagnosis. Ideally, the lesion should be excised with the laser, and this produces a specimen that can be sent for histological examination. A risk with vaporizing the lesion is that small fragments of pathological tissue may not be completely eliminated by the laser beam. This problem is more likely to occur in an area of thickly keratinized epithelium, which has a low water content and is therefore resistant to vaporization by the CO2 laser. Deep layers may not be completely eradicated and recurrence is likely to occur (Frame, 1984). In this series, five patients with cancer developed recurrences of the lesion, three presented field change, and one showed a secondary malignant lesion. The recurrence rate of 29.03% is high, but similar to the results with conventional resection of malignant lesions. The use of the CO2 laser, in spite of some advantages, seems to have the same problems as other surgical and non-surgical techniques in the treatment of invasive lesions. However, the CO2 laser is helpful in preventing intra- and post-operative complications. On the other hand, a recurrence rate of 2 out of 26 premalignant lesions is low and is similar to a previous report (Chiesa et al., 1986) and lower than others (Horch et al., 1986). The CO2 laser has an important role in treating premalignant lesions. Laser surgery has shown itself inexpensive and only minimally interferes with the patients’ normal activities. The laser reduces the amount of intra-operative bleeding compared to conventional techniques and eliminates the need for mucosa or skin grafts, which require inpatient treatment (Rhys Evans et al., 1986). Re-epithelialization following laser surgery is achieved with minimal wound contraction (Rhys Evans et al., 1986). Prolonged pain and scar formation is often observed when electrocautery is used because of tissue necrosis. Due to its high temperatures, the CO2 laser beam results in a sterile and contamination-free wound. In this present series, four out of 57 patients developed infection. However, many of the patients were in the older age group, and had additional systemic problems, which could have predisposed to such infection.

Conclusions

The carbon dioxide laser does not offer any enhanced cure-rate for oral cancer and pre-cancer, but it is a precise means of removing soft tissue lesions in selected patients. The use of the carbon dioxide laser presents several advantages over conventional techniques when treating soft-tissue pathology: lack of direct contact between the patient and the surgeon resulting in non-touch surgery; presence of a dry surgical field because of its hemostatic effect to sealing small blood vessels; wound sterilization that allows its use in necrotic or infected tissues and reduction of the risk of post-operative infection; reduction of post-operative pain due to its effect on nerve endings (patients who had both laser and electrosurgery reported less post-operative pain with laser surgery); less post-operative edema due to the sealing of small lymphatic vessels and less inflammatory response, and less contraction and scarring due to the reduction in the number of myofibrolasts during the healing process.

References

Axéll T: Occurrence of leukoplakia and some other white lesions among 20,333 adult Swedish people. Community Dent Oral Epidemiol 15: 46-51, 1987

Bánóczy J: Oral leukoplakia., Akademiaiai Kiado, Budapest 1982

Cancer Research Campaign: Factsheet 14, “Oral cancer”, CRC, London, 1990

Chiesa F, Boracchi P, Tradati N, Rossi N, Costa L, Giardini R, Marazzo M, Zurrida S: Risk of preneoplastic and neoplastic events in operated oral leukoplakias. Oral Oncol Eur Cancer 29B: 23-28, 1993

Chiesa F, Sala L, Costa L, Moglia D, Mauri M, Podrecca S, Andreola S, Marchesini R, Bandeiramonte G: Excision of oral leukoplakias by CO2 laser on an out-patient basis: A useful procedure for prevention and early detection of oral carcinomas. Tumori 72: 307-312, 1986

Flynn MB, White M, Tabah RJ: The use of carbon dioxide laser for the treatment of premalignant lesions of the oral mucosa. J Surg Oncol 37: 232-234, 1988

Frame JW: Treatment of sublingual keratosis with the CO2 laser. Br Dent J 156: 243-246, 1984

Frame JW, Das Guptas AR, Dalton GA, Rhys Evans PH: Use of the carbon dioxide laser in the management of premalignant lesion of the oral mucosa. J Laryngol Otol 98: 1251-1260, 1984

Franceschi S, Talamini R, Barra S, Baron AE, Negri E, Bidoli E, Serraino D, La Vechhi C: Smoking and drinking in relation to cancers of the oral cavity, pharynx, larynx and esophagus in Nothern Italy. Cancer Res 50: 6502-6507, 1990

Hogewind WFC, van der Waal I: Prevalence study of oral leukoplakia in a selected population of 1000 patients from the Netherlands. Community Dent Oral Epidemiol 16: 302-305, 1988

Horch H-H, Gerlarch KL, Schaefer H-E: CO2 laser surgery of oral premalignant lesions. Int J Oral Maxillofac Surg 15: 19-24, 1986

International Association of Research on Cancer: Monograph 38: Tobacco smoking. IARC, Lyon, 1986

International Association of Research on Cancer: Monograph 42: Alcooholic beverage. IARC, Lyon, 1989

Kramer IRW, El-Labban N, Lee KW: The clinical features and risks of malignant transformation in sublingual keratosis. Br Dent J 144: 171-180, 1978

Peters E, Morgan WT: Oral cancer and precancer. J Can Dent Assoc 56: 919-921, 1990

Rhys Evans PH, Frame JW, Brandrick J: A review of carbon dioxide laser surgery in the oral cavity and pharynx. J Laryngol Otol 100: 69-77, 1986

Smith CJ: Oral cancer and precancer: background, epidemiology and aetiology. Br Dent J 167: 377-383, 1989

World Health Organization: Meeting of investigators on the histological definition of precancerous lesions. WHO, 1972

World Health Organization Collaborating Centre for Oral Precancerous Lesions: Definition of leukoplakia and related lesions: an aid to studies on oral precancer. Oral Surg Oral Med Oral Pathol 46: 517-539, 1978

Correspondence: Prof. Antonio Pinheiro, Coordenação de Pós-Graduação em Odontologia, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária, 50670-420 Recife, PE, Brasil.

Accepted October 30, 1995
Electronic publication: February, 1997

BACK TO CONTENTS