English

Abstract

Introduction Molecular changes in oral leukoplakia (OL) or in adjacent ‘clinically normal mucosa’ might influence the persistence/recurrence of OL, allowing an opportunity for transformation into squamous cell carcinoma. This paper discusses the surgical management of patients with OL. Short communication Clinicians must understand that available treatment options are limited in their capacity to prevent oral cancer. Surgical resection is still currently the best technique for management of OL. Patients with OL also need to adjust their lifestyle. Conclusion We call for further studies to improve our understanding. Introduction According to a workshop coordinated by the WHO Collaborating Centre for Oral Cancer and Precancer, the term oral leukoplakia (OL) applies to ‘white plaques of questionable risk, having excluded (other) known diseases or disorders that carry no increased risk for cancer’1. OL typically presents as a white lesion of oral mucosa and is diagnosed when all other possible causes of white oral lesions are excluded1. A provisional diagnosis is made only when clinical examination is performed and any other clinical diagnosis is excluded1,2. Histological examination should support the diagnosis being mandatory for histological grading of epithelial dysplasia3. The extent or grade of dysplasia is currently the accepted reference method by which the malignant potential of OL is gauged to predict OL malignant transformation3. Key dysplastic features of stratified squamous epithelium include cellular atypia and loss of stratification4,5. Generally, dysplasia is classified by degree as mild, moderate or severe1,4,6. Despite being the gold standard method to predict malignant potential, there is little agreement between pathologists regarding epithelial dysplasia grading, and even nondysplastic lesions may transform. Subjectivity in the grading of OL, arbitrarily set grading thresholds, lack of calibration and limited knowledge of which criteria best predict malignant transformation may explain these disparities4,7,8. However, a meta-analysis has shown that the grade of dysplasia in OL and eventual malignant transformation correlate significantly9. Although excision may not eliminate this transformation, the likelihood is at least reduced9. Homogeneous OL lesions are flat, thin, uniformly white in colour and carry a low risk of malignant transformation1,2,10. On the other hand, mixed white and red lesions, with irregularly flat, nodular or verrucous areas, qualify as nonhomogeneous, and these are at high risk of progression to cancer2. The term oral verrucous leukoplakia signifies lesions with multifocal presentation that are resistant to treatment and are at a high risk of emergent cancer2. The primary risk factors for malignant transformation of OL are: (i) female gender, (ii) lesion chronicity, (iii) nonsmoker status, (iv) heterogeneous features, (v) tongue and floor of mouth sites, (vi) size >200 mm2, (vii) severity of dysplasia, (viii) aneuploidy and (xi) loss of heterozygosity2,11. Some molecular markers have shown promise in predicting the progression of premalignant oral lesions to squamous cell carcinoma, but none as yet are in routine clinical use12. Surgical techniques for managing patients with OL vary. However, randomized clinical trials have not addressed their efficacies in terms of preventing recurrent OL or its malignant transformation. This paper assesses the surgical treatment and what is achieved of patients with OL. Short Communication Treatment of OL At present, there is no scientific evidence that any manner of intervention prevents the development of squamous cell carcinoma in OL10. Recurrences may arise after surgical resection, based on mucosal field changes, which explains why widespread lesions pose a substantial threat of persistence/recurrence or malignant transformation. By definition, the concept of field cancerization denotes the presence of microscopic epithelial changes surrounding an oral cancer. Now we realize that even clinically normal mucosa, devoid of dysplasia at a microscopic level, might harbour molecular alterations predisposed to malignant transformation. Surgical excision is therefore ineffective in eradicating OL or preventing eventual malignancy. Instead, it is widely used for its potential as a diagnostic tool13. Of course, this benefit may be curtailed, if incisional biopsy is done rather than complete excision. * Corresponding author Email: rsgomez@ufmg.br 1 Department of Pathology, Biological Sciences Institute, School of Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais – Brazil 2 Department of Oral Pathology, School of Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais – Brazil