Topical application of vitamin A to oral leukoplakia: A clinical case series

The Role of Vitamins in Oral Potentially Malignant Disorders and Oral Cancer: A Systematic Review

BACKGROUND

Micronutrients are vital for general and oral health, and their potential anti-cancer properties are documented. We explore beneficial vitamins for oral potentially malignant disorders (OPMDs) and oral cancer (OC), assessing the therapeutic impacts of essential vitamin supplementation.

METHODS

We systematically review evidence on vitamin supplementation's therapeutic effects for OPMDs and OC. Relevant studies were identified through comprehensive searches of MEDLINE, Evidence-Based Medicine, and Web of Science until 16 May 2023. All studies underwent risk of bias using criteria modified from the Office of Health Assessment and Translation (OHAT) tool.

RESULTS

We analysed 80 papers. Vitamin K, studied in vitro, shows promising therapeutic potential. Vitamin C, investigated in vivo (animals and humans), demonstrated mixed animal results and generally positive human trial effects. Vitamin A's efficacy varied, with positive monotherapy or adjunct effects. Vitamins B and D showed therapeutic benefits. Oral cancer research was extensive, with a focus on oral lichen planus and oral leukoplakia among the 11 OPMDs. All bias levels were reported in 'selective reporting' and 'performance', except for "definitely high" in the 'selection', 'detection', and 'attrition/exclusion' domains.

CONCLUSIONS

Evidence of vitamin interventions for OPMDs and OC ranges from mixed to promising. Standardizing the study design and outcomes would enhance future research.

Developmental synergism in the management of oral potentially malignant disorders

Oral potentially malignant disorders (OPMDs) are associated with an increased risk of occurrence of cancers of the oral cavity or lips. The unifying theme of OPMDs is their potential risk for cancer development. Therefore, the primary objective of the management should be to prevent carcinogenesis. Beyond diagnosis, current strategies for the management of OPMDs predominantly include non-surgical and surgical interventions and a "watch-and-see" approach, such as disease monitoring or surveillance, and preventive strategies. Though no optimal clinical treatment has gained universal approval for reducing or preventing malignant development of OPMDs. Therefore, an urgent need exits for improved treatment properties and effective predictive markers for OPMDs treatment. This review aims to outline recent synergism regarding to the management of OPMDs. Developing new technologies and improved application parameters to promote the treatment efficacy and a novel management prescription approach to OPMDs are proposed.

Chemoprevention of oral cancer: A review and future perspectives

BACKGROUND

Oral cancer causes significant morbidity and mortality. Chemoprevention utilizes medication or natural compounds to reverse oral premalignant lesions and to prevent second primary tumors.

METHODS

A comprehensive PubMed database and Cochrane Library search from 1980 to 2021 was performed using the keywords "leukoplakia," "oral premalignant lesion," and "chemoprevention."

RESULTS

Chemopreventive agents included retinoids, carotenoids, cyclooxygenase inhibitor, herbal extracts, bleomycin, tyrosine kinase inhibitors, metformin, and immune checkpoint inhibitors. Although some agents demonstrated effect in reducing premalignant lesions and preventing second primary tumors, the results among different studies were highly variable.

CONCLUSIONS

The results of different trials, albeit inconsistent, provided substantial information for future studies. In the era of personalized medicine, future studies will focus on identifying specific biomarkers and molecular profile to monitor and to prevent malignant transformation. Larger trials are warranted to validate the effect of chemopreventive agents.

Mucoadhesive Nucleoside-Based Hydrogel Delays Oral Leukoplakia Canceration

Some oral squamous cell carcinomas (OSCCs) originate from preexisting oral potentially malignant disorders (OPMDs). Oral leukoplakia (OLK) is the most common and typical OPMD in the clinic, so treatment for it is essential to reduce OSCC incidence. Local chemotherapy is an option other than surgery considering the superficial site of OLK. However, there are no standardized drugs applied to OLK, and traditionally used chemotherapeutic drugs revealed limited efficacy for lack of adhesion. Hence, there is a growing demand to prepare new agents that combine mucoadhesion with an anti-OLK effect. Here, an isoguanosine-tannic acid (isoG-TA) supramolecular hydrogel via dynamic borate esters was successfully fabricated based on isoG and TA. Previously reported guanosine-TA (G-TA) hydrogel was also explored for an anti-OLK effect. Both gels not only exhibited ideal adhesive properties but also integrated anti-OLK activities in one system. In vitro cell viability indicated that isoG and TA inhibited the proliferation of dysplastic oral keratinocytes (DOKs). The in vivo OLK model evidence revealed that both gels showed potential to prevent OLK canceration. In addition, the probable anti-DOK mechanisms of isoG and TA were investigated. The results indicated that isoG could bind to adenosine kinase (ADK) and then affected the mammalian target of rapamycin (mTOR) pathway to inhibit DOK proliferation. TA could significantly and continuously reduce reactive oxygen species (ROS) in DOKs through its antioxidant effect. ROS plays an important role in the progression of cell cycle. We proved that the low level of ROS may inhibit DOK proliferation by inducing G₀/G₁ arrest in the cell cycle. Altogether, this study innovatively fabricated an isoG-TA hydrogel with ideal adhesion, and both isoG and TA showed in vitro inhibition of DOKs. Moreover, both isoG-TA and G-TA hydrogels possessed potential in delaying the malignant transformation of OLK, and the G-TA hydrogel showed a better statistical effect, providing an effective strategy for controlling OLK.

Identification of Gingivitis-Related Genes Across Human Tissues Based on the Summary Mendelian Randomization

Periodontal diseases are among the most frequent inflammatory diseases affecting children and adolescents, which affect the supporting structures of the teeth and lead to tooth loss and contribute to systemic inflammation. Gingivitis is the most common periodontal infection. Gingivitis, which is mainly caused by a substance produced by microbial plaque, systemic disorders, and genetic abnormalities in the host. Identifying gingivitis-related genes across human tissues is not only significant for understanding disease mechanisms but also disease development and clinical diagnosis. The Genome-wide association study (GWAS) a commonly used method to mine disease-related genetic variants. However, due to some factors such as linkage disequilibrium, it is difficult for GWAS to identify genes directly related to the disease. Hence, we constructed a data integration method that uses the Summary Mendelian randomization (SMR) to combine the GWAS with expression quantitative trait locus (eQTL) data to identify gingivitis-related genes. Five eQTL studies from different human tissues and one GWAS studies were referenced in this paper. This study identified several candidates SNPs and genes relate to gingivitis in tissue-specific or cross-tissue. Further, we also analyzed and explained the functions of these genes. The R program for the SMR method has been uploaded to GitHub(https://github.com/hxdde/SMR).

Management of oral leukoplakia: a position paper of the Society of Oral Medicine, Chinese Stomatological Association

OBJECTIVE

The objective of this study was to develop the first edition of a Chinese evidence-based position paper on the management of oral leukoplakia (OLK).

STUDY DESIGN

The consultant group for drafting the position paper consisted of 31 oral medicine specialists and 2 evidence-based medicine specialists. English studies (searched in PubMed, EMBASE, and the Cochrane Library) and Chinese studies (searched in China National Knowledge Infrastructure and WanFang) published before January 2018 were used. The quality of the study was assessed using the Grading of Recommendations Assessment, Development, and Evaluation grid, and the strength of the recommendations was determined based on the results of 3 rounds of voting among the consultant group members using the Delphi method.

RESULTS

Twenty-two evidence-based guidelines for clinical management and monitoring of OLK were established in this position paper. A clinical path diagram for oral health practitioners was constructed based on the recommendations.

CONCLUSION

Current evidence suggests that management and monitoring of patients with OLK should be performed by experienced clinicians to control the lesion and for early detection of malignant transformation. However, all recommendations are based on evidence of low or extremely low quality and may require further modification as new evidence is produced.

Polymeric drug delivery systems for intraoral site-specific chemoprevention of oral cancer

Oral cancer is among the most prevalent cancers in the world. Moreover, it is one of the major health problems and causes of death in many regions of the world. The traditional treatment modalities include surgical removal, radiation therapy, systemic chemotherapy, or a combination of these methods. In recent decades, there has been significant interest in intraoral site-specific chemoprevention via local drug delivery using polymeric systems. Because of its easy accessibility and clear visibility, the oral mucosa is amenable for local drug delivery. A variety of polymeric systems-such as gels, tablets, films, patches, injectable systems (e.g., millicylindrical implants, microparticles, and in situ-forming depots), and nanosized carriers (e.g., polymeric nanoparticles, nanofibers, polymer-drug conjugates, polymeric micelles, nanoliposomes, nanoemulsions, and polymersomes)-have been developed and evaluated for the local delivery of natural and synthetic chemopreventive agents. The findings of in vitro, ex vivo, and in vivo studies and the positive outcome of clinical trials demonstrate that intraoral site-specific drug delivery is an attractive, highly effective and patient-friendly strategy for the management of oral cancer. Intraoral site-specific drug delivery provides unique therapeutic advantages when compared to systemic chemotherapy. Moreover, intraoral drug delivery systems are self-administrable and can be removed when needed, increasing patient compliance. This article covers important aspects and advances related to the design, development, and efficacy of polymeric systems for intraoral site-specific drug delivery. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1383-1413, 2018.

Topical agents for oral cancer chemoprevention: A systematic review of the literature

OBJECTIVES/HYPOTHESIS

We review the use of topical chemoprevention agents in patients with oral potentially malignant disorders (PMD).

METHODS

A systematic review of studies on topical chemoprevention agents for oral PMD from 1946 to November 2016 was conducted using the MEDLINE database, Embase, and Cochrane Library. Data were extracted and analyzed from selected studies including study type, sample size, demographics, treatment length, response rate, follow-up time, adverse effects, and recurrence.

RESULTS

Of 108 studies, twenty-four, representing 679 cases met the inclusion criteria. The clinical lesions evaluated included oral leukoplakia, erythroplakia (OEL), verrucous hyperplasia (OVH), oral lichen planus, larynx squamous cell carcinoma, and oral squamous cell carcinoma (OSCC). The mean complete response rate for topical retinoid therapy was 32%. The mean complete response rate for 1% bleomycin therapy and 0.5% bleomycin was 40.2% and 25%, respectively. The complete response rate of OVH, OEL, and OSCC to photodynamic therapy ranged from 66.7% to 100%.

CONCLUSION

There are a paucity of data examining topical treatment of oral PMDs. However, the use of topical agents among patients with oral lesions may be a viable complement or even alternative to traditional surgery, radiation, or systemic chemotherapy, with the advantage of reducing systemic side effects and sparing important anatomic structures. This study of 679 cases represents the largest pooled sample size to date, and the preliminary studies in this systematic review provide support for further inquiry.

Mobile health application for remote oral cancer surveillance

BACKGROUND

To determine the effectiveness of a mobile phone-based remote oral cancer surveillance program (Oncogrid) connecting primary care dental practitioners and frontline health care workers (FHW) with oral cancer specialists.

METHODS

The study population (N = 3,440) included a targeted cohort (n = 2,000) and an opportunistic cohort (n = 1,440) screened by FHW and dental professionals, respectively. The authors compared the screening efficacy in both groups, with specialist diagnosis considered the reference standard. The outcomes measured were lesion detection and capture of interpretable images of the oral cavity.

RESULTS

In the targeted cohort, among 51 of 81 (61%) interpretable images, 23 of 51 (45%) of the lesions were confirmed by specialists, while the opportunistic cohort showed 100% concordance with the specialists (106 of 106). Sixty-two of 129 (48%) of the recommended patients underwent biopsy; 1 of 23 (4%) were in the targeted cohort, and 61 of 106 (57%) were in the opportunistic cohort. Ninety percent of the lesions were confirmed to be malignant or potentially malignant.

CONCLUSIONS

The mobile health-based approach adopted in this study aided remote early detection of oral cancer by primary care dental practitioners in a resource-constrained setting. Further optimization of this program is required to adopt the system for FHW. Evaluation of its efficacy in a larger population is also warranted.

PRACTICAL IMPLICATIONS

The increased efficiency of early detection by dentists, when assisted by a remote mobile health-based approach, is a step toward a more effective oral cancer screening program.

Photodynamic therapy: a review and its prospective role in the management of oral potentially malignant disorders

With the unreliability of epithelial dysplasia as a predictor to determine the risk of future malignant development, subjectivity associated in evaluating dysplasia by pathologists and paucity of biomarkers that could accurately predict the progression risks in oral potentially malignant disorders (PMDs), eradication of the lesions appears to be the most desirable approach to minimize the risk of invasive cancer formation. Interventions, such as surgery and chemoprevention, have not shown promising long-term results in the treatment of these lesions, and lack of guidelines and general consensus on their management has incited much anxiety and doubts in both patients and community clinicians. Topical photodynamic therapy (PDT) is a minimally invasive and minimally toxic technique that in recent years has shown great promise in the management of PMDs. In this review, we describe the historical developments in the field of PDT, its basic mechanisms, as well as related clinical studies, and its challenges in the management of oral PMDs. Based on its high efficacy and low side effects, its high patient acceptance/compliance, the simplicity of the procedure and its minimal pretreatment preparation, topical PDT is believed to have potential to play an important role in the management of PMDs, especially of the low-grade dysplasia.

Nanostructured lipid carriers loaded with tributyrin as an alternative to improve anticancer activity of all-trans retinoic acid

OBJECTIVES

All-trans retinoic acid (ATRA) is one of the most successful examples of differentiation agents and histone deacetylase inhibitors, such as tributyrin (TB), are known for their antitumor activity and potentiating action of drugs, such as ATRA. Nanostructured lipid carriers (NLC) represent a promising alternative to the encapsulation of lipophilic drugs such as ATRA. This study aims to develop, characterize and evaluate the cytotoxicity of ATRA-TB-loaded NLC for cancer treatment.

METHODS

The influence of in situ formation of an ion pairing between ATRA and a lipophilic amine (benethamine) on the characteristics of NLC (size, zeta potential, encapsulation efficiency) was evaluated. TB, a butyric acid donor, was used as a component of the lipid matrix. In vitro activity on cell viability and distribution of cell cycle phases were evaluated for MCF-7, MDA-MB-231, HL-60 and Jurkat cell lines.

RESULTS

The presence of the amine significantly increased the encapsulation efficiency of ATRA in NLC. Inhibition of cell viability by TB-ATRA-loaded NLC was more pronounced than the free drug. Analysis of the distribution of cell cycle phases also showed increased activity for TB-ATRA-loaded NLC, with the clear effect of cell cycle arrest in G0/G1 phase transition. The presence of TB played an important role in the activity of the formulation.

CONCLUSION

Taken together, these findings suggest that TB-ATRA-loaded NLC represents a promising alternative to intravenous administration of ATRA in cancer treatment.

Oral lichen planus (OLP), oral lichenoid lesions (OLL), oral dysplasia, and oral cancer: retrospective analysis of clinicopathological data from 2002-2011

INTRODUCTION

This 10-year retrospective study analyzed the incidence of malignant transformation of oral lichen planus (OLP). The study also included dysplasia and oral lichenoid lesion (OLL) in the initial biopsy as a potential differential diagnosis.

MATERIAL AND METHODS

A total of 692 scalpel biopsies were taken from 542 patients (207 [38.2%] men and 335 [61.8%] women). Clinical and histopathological parameters were analyzed.

RESULTS

The parameters gender (p = 0.022) and smoking behavior (p < 0.001) were significantly associated with the severity of diagnosis. Mucosal lesions with an ulcerative appearance (p = 0.006) and those located on the floor of the mouth (p < 0.001) showed significantly higher degrees of dysplasia or were diagnosed as oral squamous cell carcinoma (OSCC). Smoking and joint disease appeared to be significant risk factors. Treatment with tretinoin in different concentrations (0.005-0.02%) significantly improved diagnosis. Twelve patients (8 female, 4 male) showed malignant transformation to OSCC within an average period of 1.58 years. The malignant transformation rate (MTR) was higher for OLL (4.4%) than OLP (1.2%). If the first biopsy showed intraepithelial neoplasia, the risk of developing OSCC increased (by 3.5% for squamous intraepithelial neoplasia (SIN) II and by 6.7% for SIN III).

CONCLUSION

Although we cannot rule out that OLP is a premalignant oral condition, we can confirm that OLP had the lowest MTR of all diagnoses.

Estimation of oral leukoplakia treatment records in the research of the Department of Maxillofacial and Oral Surgery, Medical University of Gdansk

Introduction

Oral leukoplakia (OL) is the most common potentially malignant lesion of the oral cavity.

Aim

The purpose of the study was clinical and epidemiological analysis of patients with OL diagnosed and treated in the Department of Maxillofacial and Oral Surgery, Medical University of Gdansk, comparison of effectiveness of treatment methods, defining whether van der Waal level of OL influences treatment effectiveness, correlation between localization of OL and treatment effectiveness, and defining the optimal OL therapeutic method.

Material and methods

Among 55 911 patients diagnosed and treated in the Department in the years 1999–2009, 204 people with OL were selected (104 women, 100 men, average age: 58.1 years). Treatment and observation period of 6 months was completed by 178 (87.25%) patients. Seventy-four patients were treated with cream containing 0.05% tretinoin. Sixty-three patients underwent cryosurgery, and 41 surgery. Control visits were made in week 2, 4, 6 and 8 and 6 months after completed treatment.

Results

Three hundred and twenty lesions of OL were diagnosed. According to van der Waal classification, the largest group of patients was classified into stage I and II. The percentage of totally cured patients was 90.07%. There were no statistic differences in effectiveness between surgical and cryosurgical treatment.

Conclusions

Evaluation of OL treatment methods depends on localization of the lesions and its stage of progression. The effectiveness of treatment with locally applied tretinoin is smaller in comparison to surgery and cryosurgery. It allows to reduce the number and size of OL lesions, what makes it possible to reduce the number of ablative procedures.

Is the 810-nm diode laser the best choice in oral soft tissue therapy?

Objective:

To evaluate the safety and efficacy of an 810-nm diode laser for treatment of benign oral soft tissue lesions.

Materials and Methods:

Treatment with the 810-nm diode laser was applied to a group of eighteen patients with pathological frenulum and epulis fissuratum; five patients with oral lichen planus, oral leukoplakia, and mucous membrane pemphigoid; and four patients with pyogenic granuloma.

Results:

Although the conventional surgery wound heals in a fairly short time, in the present study, the simple oral soft tissue lesions healed within two weeks, the white and vesiculobullous lesions healed completely within six weeks, and the pyogenic granuloma lesions healed within four weeks. Any complication was treated by using the 810-nm diode laser.

Conclusions:

Patient acceptance and satisfaction, without compromising health and function, have been found to be of a high degree in this present study. Thus, we can say that the use of the 810-nm diode laser may indeed be the best choice in oral soft tissue surgery.

Optimizing therapeutic efficacy of chemopreventive agents: A critical review of delivery strategies in oral cancer chemoprevention clinical trials

Due to its characterized progression from recognized premalignant oral epithelial changes (i.e., oral epithelial dysplasia) to invasive cancer, oral squamous cell carcinoma represents an optimal disease for chemopreventive intervention prior to malignant transformation. The primary goal of oral cancer chemoprevention is to reverse, suppress, or inhibit the progression of premalignant lesions to cancer. Over the last several decades, numerous oral cancer chemoprevention clinical trials have assessed the therapeutic efficacy of diverse chemopreventive agents. The standard of care for more advanced oral dysplastic lesions entails surgical excision and close clinical follow-up due to the potential (~33%) for local recurrence at a similar or more advanced histological stage. The purpose of this review was to identify prominent oral cancer chemoprevention clinical trials, assess their overall therapeutic efficacy, and delineate effects of local versus systemic drug administration. In addition, these compiled clinical trial data present concepts for consideration in the design and conduction of future clinical trials.

Local drug delivery for oral mucosal diseases: challenges and opportunities

There are few topical formulations used for oral medicine applications most of which have been developed for the management of dermatological conditions. As such, numerous obstacles are faced when utilizing these preparations in the oral cavity, namely enzymatic degradation, taste, limited surface area, poor tissue penetration and accidental swallowing. In this review, we discuss common mucosal diseases such as oral cancer, mucositis, vesiculo-erosive conditions, infections, neuropathic pain and salivary dysfunction, which could benefit from topical delivery systems designed specifically for the oral mucosa, which are capable of sustained release. Each condition requires distinct penetration and drug retention profiles in order to optimize treatment and minimize side effects. Local drug delivery may provide a more targeted and efficient drug-delivery option than systemic delivery for diseases of the oral mucosa. We identify those mucosal diseases currently being treated, the challenges that must be overcome and the potential of novel therapies. Novel biological therapies such as macromolecular biological drugs, peptides and gene therapy may be of value in the treatment of many chronic oral conditions and thus in oral medicine if their delivery can be optimized.

Oral premalignant lesions: from a clinical perspective

In this review article, the clinical and histopathological characteristics of oral premalignant lesions, and primarily oral leukoplakia, are noted and the risk factors for malignant transformation of oral leukoplakia are discussed. Malignant transformation rates of oral leukoplakia range from 0.13 to 17.5%. The risk factors of malignant transformation in the buccal mucosa and labial commissure are male gender with chewing tobacco or smoking in some countries such as India, or older age and/or being a non-smoking female in other countries. Some authors have reported that leukoplakia on the tongue or the floor of the mouth showed a high risk of malignant transformation, although others have found no oral subsites at high risk. In concurrence with some authors, the authors of this review view epithelial dysplasia as an important risk factor in malignant transformation; however, there are conflicting reports in the literature. Many authors believe that nonhomogeneous leukoplakia is a high risk factor without exception, although different terms have been used to describe those conditions. The large size of lesions and widespread leukoplakia are also reported risk factors. According to some studies, surgical treatment decreased the rate of malignant transformation; however, many review articles state that no definitive treatment including surgery can decrease the malignant transformation rate of oral leukoplakia because of the lack of randomized control trials of treatment. Tobacco chewing and smoking may be causative agents for cancerization of oral leukoplakia in some groups, and evidence for a role of human papilloma virus in the malignant transformation of oral leukoplakia is inconsistent. Further research to clarify its role in malignant transformation is warranted.

A review of the nonsurgical treatment of oral leukoplakia

The aim of this paper was to assess the nonsurgical treatment of oral leukoplakia (OL). A medline search from 1983 to 2009 was conducted. The topical or systemic nonsurgical treatments or combination of both was reviewed. The primary outcomes of interest were clinical resolution, malignant transformation, follow-up, and recurrence of OL. Studies showed a rate higher than 50% of clinical resolution with photodynamic therapy, beta-carotene, lycopene, or vitamin A. Few studies reported rates of recurrence from 5 to 67% and of malignant transformation from 8 to 23%. There is a lack of randomized clinical trials that assess the effectiveness of nonsurgical treatment of OL. At this time, randomized controlled trials for nonsurgical treatment of OL demonstrate no evidence of effective treatment in preventing malignant transformation and recurrence. It reinforces that even after clinical resolution, OL should be regularly followed.

Vitamin A deficiency causes metaplasia in vocal fold epithelium: a rat study

OBJECTIVES

The roles of vitamin A in the vocal fold epithelium are not well documented, although vitamin A has been used as a conservative treatment for laryngeal leukoplakia. The purpose of this study was to analyze the roles of vitamin A in vocal fold epithelial differentiation.

METHODS

Vitamin A-deficient (VAD) rats were generated, and the abnormality of their vocal fold epithelium was examined by hematoxylin and eosin staining and immunohistochemical analysis for keratin 10 and transglutaminase (TGase) 1.

RESULTS

The VAD experimental rats exhibited orthokeratosis of the vocal fold epithelium. Keratin 10 and TGase 1 were up-regulated in the epithelium of the VAD rats.

CONCLUSIONS

It is suggested that vitamin A suppresses TGase 1 expression in normal vocal folds to inhibit keratinization, and that the TGase 1 up-regulation caused by vitamin A deficiency may be related to the formation of metaplasia in the laryngeal epithelium.

Three-year follow-up of oral leukoplakia after neodymium:yttrium aluminum garnet (Nd:YAG) laser surgery

Oral leukoplakia is a relatively common lesion with a significant proportion of cases changing into cancer. Since most leukoplakias are asymptomatic, the primary objective of treatment must aim at the prevention of such malignant transformation. The main objectives of the study are to observe (1) the efficacy, safety and acceptability of the neodymium:yttrium aluminum garnet (Nd:YAG) laser in the management of oral leukoplakia; (2) the nature of postoperative complications, if any, associated with laser ablation, and (3) the 3-year prognosis of oral leukoplakia treated with laser. Twenty-eight patients with histologically proven leukoplakia were treated with Nd:YAG laser. From this study, we observed that the patients treated with Nd:YAG laser had only mild to moderate pain, swelling and restricted mouth opening, which peaked between 72 h and 1 week. In a majority of the patients the healing was prolonged, to a maximum of 5 weeks, and there was no clinical evidence of scarring in 26 out of 28 cases. In this study we achieved a cure rate of 92.86% in a 6-month period. Further follow-up after 3 years yielded almost the same result, except that one patient was not available for follow-up. We concluded that Nd:YAG laser is an effective device in the management of oral leukoplakia, which is one of the major pre-cancerous lesions in our country.

Laser assisted topical ‘biofilm’ chemoprevention of oral cancer

This study examines whether a combination of laser microvascular targeting, mucosal adhesive film (MAF) and retinoic acid (RA) techniques would improve the efficacy for oral cancer chemoprevention. The cheek pouches of 48 hamsters were painted with 7,12-dimethlbenz[a]nthrancene to produce premalignant lesions. There were four groups of 12 each: (1) control; (2) pulsed dye laser (PDL) treatment; (3) topical MAF/RA patch treatment; and (4) combined treatment of PDL and MAF/RA. The treatments were conducted for 27 days. Our findings indicate that this new combined treatment is safe and effective for oral cancer chemoprevention, and warrants further study.

Management of oral leukoplakia by laser surgery: relation between recurrence and malignant transformation and clinicopathological features

OBJECTIVE

The aim of the present study was to assess the clinical usefulness of laser surgery for oral leukoplakia.

BACKGROUND

Recurrence and/or malignanT transformation of oral leukoplakia have occasionally been observed following laser surgery. It is reported that the rate of recurrence was 7.7-38.1%, while malignant transformation was 2.6-9%.

MATERIALS AND METHODS

A total of 154 oral leukoplakias from 116 patients were treated in our department. Comparisons with the rate of recurrence, malignant transformation and clinical futures, epithelial dysplasia, location, and treatment procedure were examined. To evaluate recurrence and malignant transformation, the cases were restricted to those with a minimum follow-up of 6 months.

RESULTS

A total of 97 lesions fulfilled this criterion. The rate of recurrence had no association with the location or the epithelial dysplasia, although it differed with the treatment procedure. The rate of recurrence in laser surgery was approximately 29%. Malignant transformation was observed in four of 97 lesions. They were observed in 13.6% of tongue cases and 1.8% of gingival cases. Three of four lesions were treated with excision surgery, and the remaining one treated with laser vaporization. Only 1.2% malignant transformation in laser surgery was revealed.

CONCLUSION

Laser excision is suitable for leukoplakia cases on non-keratinized epithelia (i.e., the tongue and buccal mucosa), while laser vaporization is suitable for the gingival cases. Management of oral leukoplakia prevents not only recurrence and malignant transformation, but also postoperative dysfunction. We believe that laser surgery is an excellent procedure.

Laser surgery as a treatment for oral leukoplakia

Various treatment procedures for oral leukoplakia have been reported. However, after some treatments, oral leukoplakia show recurrence and/or malignant transformation, even following complete resection. Furthermore, patients with oral leukoplakia may develop new lesions in other oral cavity locations. Laser surgery for oral mucosal lesions has been reported to have many advantages, and it is widely used in the treatment of oral leukoplakia. In previous studies, recurrence and malignant transformation from the lesion have occasionally been observed following laser surgery. We reviewed the records of oral leukoplakia patients treated with laser surgery to assess its clinical usefulness. It has been reported that the rate of recurrence was 7.7-38.1%, while malignant transformation was 2.6-9% for oral leukoplakia treated with laser surgery. In the present study, there was 29.3% recurrence and 1.2% malignant transformation after laser surgery. This was similar to previous findings. This suggests that non-homogeneous leukoplakia on nonkeratinized epithelia, i.e. the tongue mucosa has a high risk for malignant transformation, so lesions should be excised after detecting abnormal epithelia using vital tissue staining. The wound healing process after laser surgery was satisfactory and no significant complications were observed. Management of oral leukoplakia prevents not only recurrence and malignant transformation, but also postoperative dysfunction: laser surgery is an excellent procedure that is able to overcome these problems.

Carcinogenesis and cyclooxygenase: the potential role of COX-2 inhibition in upper aerodigestive tract cancer

Cyclooxygenase-2 (COX-2) is upregulated in a number of epithelial cancers, including in upper aerodigestive tract (UADT) premalignant and malignant lesions. The purpose of this review is to provide a comprehensive examination of the potential of COX-2 inhibition in prevention of UADT premalignant and malignant disease. A Medline and Cancerlit literature search was conducted for the period 1993-2002, and identified literature was reviewed. There is evidence from in vitro studies, as well as animal models, that inhibition of COX-2 may suppress carcinogenesis by affecting a number of pathways of carcinogenesis, promoting apoptosis and inhibiting angiogenesis. Preliminary studies of gastro-intestinal (GI) carcinogenesis suggest that COX-2 inhibitors may represent an approach to the chemoprevention of epithelial cancers. COX-2 inhibitors may have a potential role in chemoprevention of UADT cancer, and clinical trials appear warranted.

Topical inhibition of oral carcinoma cell with polymer delivered celecoxib

Celecoxib has a potential role for oral cancer chemoprevention but its systemic side effects are a concern. Topical chemoprevention is a promising way to reduce the toxicity. This study was designed to determine whether topical application of polymer delivered celecoxib would have an inhibitory effect on human oral carcinoma cells. Seventeen nude mice were intradermally inoculated with the carcinoma cells, and then were divided into control and treatment groups. Tumor growth was measured for 15 days, at which significant difference was found between two groups (P<0.001). This study indicates a potential role of polymer film delivered celecoxib for topical inhibition of oral cancer.

Oral lichen planus: progress in understanding its malignant potential and the implications for clinical management

Oral lichen planus (OLP) is an inflammatory lesion that has malignant potential, but few cases of OLP progress to malignancy. A diagnosis of OLP should be confirmed on the basis of historical, clinical, and histologic data. The presence of dysplasia in an OLP-like lesion increases the risk of malignant transformation, mandating management and close follow-up. A molecular assessment of OLP may provide the best evidence of malignant risk and will likely become available for clinical use. In addition, exfoliated cells may be examined for loss of heterozygosity and may become a valuable clinical tool for patient follow-up. The treatment of OLP should include elimination of tissue irritants and recurring exposure to oral carcinogens. If OLP is symptomatic, appropriate treatment with immunosuppressive medications, particularly corticosteroids, should be undertaken. For lesions with dysplastic changes, management may include attention directed to the inflammatory change and follow-up biopsies to assess residual histologic changes that may represent dysplasia. Dysplastic OLP may be best treated as other oral dysplastic conditions; thus, regular, more frequent follow-up is required.

Progress and perspectives in chemoprevention of head and neck cancer

Head and neck squamous cell carcinoma is ideally suited for chemoprevention efforts. Elucidation of molecular events underlying head and neck cancer has facilitated the development of preventive strategies. Landmark trials of 13-cis retinoic acid demonstrated that chemoprevention of head and neck cancer is indeed possible. New agents targeting specific molecular abnormalities contributing to the multifocal and multistep process of carcinogenesis have been identified. Innovative approaches to the study of chemoprevention, such as the use of biomarker intermediate end points, can select agents with particular promise for more definitive trials. However, barriers to progress in chemoprevention remain, including the validation of surrogate end point biomarkers and identification of safe and well-tolerated agents with the ability to delay carcinogenesis.

The effect of retinoids on premalignant oral lesions: focus on topical therapy

BACKGROUND

Retinoids have been studied as chemopreventive treatment for patients with oropharyngeal carcinoma. Vitamin A modulates growth and differentiation of cells, and its deficiency enhances susceptibility to carcinogenesis. The chemopreventive mechanism of action of vitamin A is discussed, and a review of clinical results and side effects of the systemic use of vitamin A is included. The objective of the current report was to review the possible role of topical vitamin A and vitamin A derivatives in the management of patients with oral lesions with a risk of transformation to carcinoma.

METHODS

A Medline search was conducted and references identified within the identified papers were also reviewed.

RESULTS

Only four studies using topical vitamin A for patients with oral leukoplakia have been reported. A complete response was achieved in 10-27% of patients, and a partial response was achieved in 54-90% of patients; however, recurrence of leukoplakia was reported after withdrawing the medication in approximately 50% of patients. The side effects of the topical use were minimal.

CONCLUSIONS

Although the direct application of higher concentrations of retinoic acid results in suppression of oral leukoplakias only, its use in the treatment of patients with recurrent and persistent lesions may be justified for controlling lesions that otherwise may progress. Further controlled clinical studies are needed.

Retinoids and their receptors in cancer development and chemoprevention

Retinoids play an important role in regulating the growth and differentiation of normal, premalignant and malignant cell types, especially epithelial cells, mainly through interaction with two types of nuclear receptors: retinoic acid receptors (RARalpha, beta and gamma) and retinoid X receptors (RXRalpha, beta and gamma). Vitamin A deficiency in experimental animals has been associated with a higher incidence of cancer and with increased susceptibility to chemical carcinogens. This is in agreement with the epidemiological studies indicating that individuals with a lower dietary vitamin A intake are at a higher risk to develop cancer. At the molecular level, aberrant expression and function of nuclear retinoid receptors have been found in various types of cancer including premalignant lesions. Thus, aberrations in retinoid signaling are early events in carcinogenesis. Retinoids at pharmacological doses exhibit a variety of effects associated with cancer prevention. They suppress transformation of cells in vitro, inhibit carcinogenesis in various organs in animal models, reduce premalignant human epithelial lesions and prevent second primary tumors following curative therapy for epithelial malignancies such as head and neck, lung, liver, and breast cancer.