Excision of Oral Leukoplakias by CO2 Laser on an Out-Patient Basis: A Useful Procedure for Prevention and Early Detection of Oral Carcinomas

Early-Phase Interventional Trials in Oral Cancer Prevention

Simple Summary

Oral cancer is a devastating disease with increasing incidence worldwide. Oral epithelial dysplasia (OED) is a potentially malignant disorder and patients with OED are at increased risk of developing oral cancer. Current strategies for management of OED include surgery or close observation and both fail to address the underlying pathogenesis of the disease. There is an urgent need for evidence-based medical treatments for OED to prevent oral cancer development in this cohort. Chemoprevention trials to date have not delivered therapeutic agents for routine clinical practice. Historically, there has been significant heterogeneity in the design of oral cancer chemoprevention trials, with most failing to selectively recruit patients with biopsy-proven OED, which limits the usefulness of the findings in the OED population. The present paper aims to review the current evidence and the methodology of early-phase trials in oral cancer chemoprevention. Novel strategies in oral cancer chemoprevention will also be discussed.

Abstract

The increasing breadth of molecular targets, promise of immune-targeted therapies and repurposed agents have heightened interest in cancer prevention. While, to date, testing of oral cancer chemoprevention strategies has failed to deliver therapeutic agents for routine clinical practice, there remains an urgent need for further clinical research to overcome this hurdle. Patients at the greatest risk of disease stand to benefit the most from inclusion in clinical trials; therefore, there is a need to carefully define this population using validated clinical and molecular markers. Safety, tolerability and the efficacy of interventions is assessed through carefully selected endpoints. These endpoints may include pharmacodynamic, clinical, histological and on-target molecular modifications as an individual or as a composite endpoint. Early-phase trials provide an area of opportunity to explore novel and repurposed agents in the setting of oral cancer chemoprevention, eventually leading to phase III trials with clinical endpoints such as transformation and clinical outcome; these studies are large, lengthy and expensive and should be reserved for the most promising of agents. This paper will explore current evidence in oral cancer chemoprevention, drug repurposing, selection of appropriate endpoints for early-phase trials and novel therapeutic angles in oral cancer chemoprevention.

UK consensus recommendations on the management of oral epithelial dysplasia during COVID-19 pandemic outbreaks

OBJECTIVES

Oral Epithelial Dysplasia (OED) is associated with an increased risk of oral cancer development. The SARS-CoV-2 pandemic is necessitating the suspension or dramatic reduction of face-to-face non-urgent elective services, including OED clinics. Little is known regarding the potential impact of elective services suspension upon the risk of OED progression, and whether alternative strategies (e.g. remote consultations) may be introduced to ensure OED surveillance. The aim of this paper is to provide expert-opinion consensus recommendations for the management of OED during the current and future pandemic outbreaks.

MATERIALS AND METHODS

A working group of nine UK-based senior clinicians and academics in Oral and Maxillofacial Surgery and Oral Medicine was created and twelve consensus statements were developed using a modified-Delphi process. Greater than 80% agreement was considered a consensus.

RESULTS

Consensus was achieved for all twelve statements (89-100% agreement). The group agreed that, during the temporary suspension of elective services associated with COVID-19 pandemic outbreaks, patients with OED can be risk stratified to determine the length of accepted delay in face-to-face consultation. Remote consultations with patient-provided clinical photographs may be a useful way of maintaining a level of surveillance in this group of patients.

CONCLUSIONS

Using an expert working group methodology, we have developed consensus recommendations for the monitoring of individuals with OED during pandemic outbreaks associated with temporary suspension of elective services. This has identified areas of future research and highlighted the need for a stronger evidence base to inform the set-up and delivery of surveillance regimens for patients with OED.

Long-term follow-up of oral epithelial dysplasia: A hospital based cross-sectional study

Background/purpose

Oral epithelial dysplasia (OED) is characterized histopathologically by cellular and morphological changes that remain the single most important factor predicting risk for subsequent development of invasive neoplasia. Hence the aims of the present study were to determine the rate of malignant change of OED in a group of patients followed-up for a number of years, and hence determine factors likely to influence this malignant change, and to describe the clinical characteristics of patients who developed recurrence of OED and second dysplastic lesions.

Materials and methods

This is hospital based cross-sectional study of all biopsy reports with histologically confirmed OED between 2012 and 2018 were retrospectivelly reviewed.

Results

A total of 359 patients with histologically confirmed OED were reviewed, twenty (5.5%) of the 359 patients developed an invasive squamous cell carcinoma (SCC) of the oral mucosa over a period of 2 to 274 months with mean transformation time of 3.3 years.

Conclusion

The high risk of malignant transformation of OED seems to be related to patients older than 50 years when lesions were on the floor of mouth with severe dysplastic changes.

Oral epithelial dysplasia: Causes, quantification, prognosis, and management challenges

Oral epithelial dysplasia is a spectrum of architectural and cytological epithelial changes caused by accumulation of genetic changes, and is associated with an increased risk of progression to squamous cell carcinoma. It is a microscopic diagnosis of immense clinical importance. The initial reports of oral potentially malignant disorders with oral epithelial dysplasia transforming to oral cancer helped in understanding the nature of oral malignancies. Since then, clinical studies on oral potentially malignant disorders have combined microscopic findings of oral epithelial dysplasia to assess the malignant transformation potential of different grades of epithelial dysplasia. A significant amount of scientific literature has amassed on oral epithelial dysplasia relating to aspects of its diagnosis and management. However, the evidence base is weak as a result of the significant variability of published research. Poorly described study methods, variability in different oral epithelial dysplasia grading systems, inter- and intra-examiner variability causing issues of reliability, inadequate sample size, and inconsistent durations of follow-up are some of the methodological issues contributing to the failure to provide dependable information. Randomized clinical trials on the malignant transformation potential of oral epithelial dysplasia and its treatment outcomes are limited. This comprehensive literature review on oral epithelial dysplasia summarizes the scientific knowledge published in the scientific literature in English since its first description. The historical development, etiological factors, grading systems, diagnostic criteria, assessment of risk factors and prevention of malignant transformation, management principles of different grades of oral epithelial dysplasia (surgical and nonsurgical), recommendations on follow-up, and prognostic indicators are discussed in detail.

Advances toward fully automated in vivo assessment of oral epithelial dysplasia by nuclear endomicroscopy-A pilot study

BACKGROUND

Uncertainties in detection of oral epithelial dysplasia (OED) frequently result from sampling error especially in inflammatory oral lesions. Endomicroscopy allows non-invasive, "en face" imaging of upper oral epithelium, but parameters of OED are unknown.

METHODS

Mucosal nuclei were imaged in 34 toluidine blue-stained oral lesions with a commercial endomicroscopy. Histopathological diagnosis showed four biopsies in "dys-/neoplastic," 23 in "inflammatory," and seven in "others" disease groups. Strength of different assessment strategies of nuclear scoring, nuclear count, and automated nuclear analysis were measured by area under ROC curve (AUC) to identify histopathological "dys-/neoplastic" group. Nuclear objects from automated image analysis were visually corrected.

RESULTS

Best-performing parameters of nuclear-to-image ratios were the count of large nuclei (AUC=0.986) and 6-nearest neighborhood relation (AUC=0.896), and best parameters of nuclear polymorphism were the count of atypical nuclei (AUC=0.996) and compactness of nuclei (AUC=0.922). Excluding low-grade OED, nuclear scoring and count reached 100% sensitivity and 98% specificity for detection of dys-/neoplastic lesions. In automated analysis, combination of parameters enhanced diagnostic strength. Sensitivity of 100% and specificity of 87% were seen for distances of 6-nearest neighbors and aspect ratios even in uncorrected objects. Correction improved measures of nuclear polymorphism only. The hue of background color was stronger than nuclear density (AUC=0.779 vs 0.687) to detect dys-/neoplastic group indicating that macroscopic aspect is biased.

CONCLUSIONS

Nuclear-to-image ratios are applicable for automated optical in vivo diagnostics for oral potentially malignant disorders. Nuclear endomicroscopy may promote non-invasive, early detection of dys-/neoplastic lesions by reducing sampling error.

Mouth Cancer for Clinicians Part 6: Potentially Malignant Disorders

A MEDLINE search early in 2015 revealed more than 250,000 papers on head and neck cancer; over 100,000 on oral cancer; and over 60,000 on mouth cancer. Not all publications contain robust evidence. We endeavour to encapsulate the most important of the latest information and advances now employed in practice, in a form comprehensible to healthcare workers, patients and their carers. This series offers the primary care dental team, in particular, an overview of the aetiopathogenesis, prevention, diagnosis and multidisciplinary care of mouth cancer, the functional and psychosocial implications, and minimization of the impact on the quality of life of patient and family.

CLINICAL RELEVANCE

This article offers the dental team an overview of oral potentially malignant disorders.

The Diagnostic Accuracy of Incisional Biopsy in the Oral Cavity

PURPOSE

To determine the accuracy of incisional biopsy examination to diagnose oral lesions.

MATERIALS AND METHODS

This retrospective cohort study was performed to determine the concordance rate between incisional biopsy examination and definitive resection diagnosis for different oral lesions. The study sample was derived from the population of patients who presented to the Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital (Boston, MA) from January 2005 through December 2012. Inclusion criteria were the diagnosis of an oral lesion from an incisional biopsy examination, subsequent diagnosis from the definitive resection of the same lesion, and complete clinical and pathologic patient records. The predictor variables were the origin and size of the lesion. The primary outcome variable was concordance between the provisional incisional biopsy diagnosis and definitive pathologic resection diagnosis. The secondary outcome variable was type of biopsy error for the discordant cases. Incisional biopsy errors were assessed and grouped into 5 categories: 1) sampling error; 2) insufficient tissue for diagnosis; 3) presence of inflammation making diagnosis difficult; 4) artifact; and 5) pathologist discordance.

RESULTS

A total of 272 patients met the inclusion criteria. The study sample had a mean age of 47.4 years and 55.7% were women. Of these cases, 242 (88.9%) were concordant when comparing the biopsy and final resection pathology reports. At histologic evaluation, 60.0% of discordant findings were attributed to sampling error, 23.3% to pathologist discrepancy, 13.3% to insufficient tissue provided in the biopsy specimen, and 3.4% to inflammation obscuring diagnosis. Overall, concordant cases had a larger average biopsy volume (1.53 cm(3)) than discordant cases (0.42 cm(3)).

CONCLUSION

The data collected indicate an 88.9% diagnostic concordance with final pathologic results for incisional oral biopsy diagnoses. Sixty percent of discordance was attributed to sampling error when sampled tissue was not representative of the lesion in toto. Multiple-site biopsy specimens and larger-volume samples allowed for a more accurate diagnosis.

Challenges in predicting which oral mucosal potentially malignant disease will progress to neoplasia

Probably the greatest challenge to those managing patients with oral diseases is the dilemma of attempting to predict which oral erythroplakias, leukoplakias, lichenoid and other potentially malignant mucosal disease (PMD) such as oral submucous fibrosis will progress to neoplasia--notably oral squamous cell carcinoma (OSCC). The paper reviews progress over the past decade and the application to the clinical situation.

Overview of cancer for the healthcare team: aetiopathogenesis and early diagnosis

Much cancer presents late, at a stage when not only is more radical treatment necessary, but the prognosis is also less favourable. This paper attempts to provide an overview of the aetiopathogenesis of cancer (carcinoma) for the healthcare team, a broad understanding of which is crucial for coping with issues related to prevention, diagnosis and management. Prevention of cancer involves lifestyle decisions which afford protection not only against cancers in many sites, but also against a wide range of other conditions, many of which are equally life-threatening. The paper also highlights areas of controversy in the early diagnosis of oral cancer. Earlier diagnosis is likely to be achieved reliably only with the introduction of molecular studies.

Factors affecting carbon dioxide laser treatment for oral precancer: a patient cohort study

BACKGROUND

Although the benefits of CO(2) laser surgery in oral precancer management have been evaluated, little consideration has been given to the factors which may influence treatment outcome, especially amongst patients developing recurrence or malignant transformation.

STUDY DESIGN

Seventy eight patients (51 males, 27 females; mean age 57.8 years) undergoing CO(2) laser excision of single, new dysplastic oral precancer lesions (OPLs) were followed up for a minimum of 2 years and the influence of clinico-pathological parameters, socio-demographic factors and the presence or absence of residual dysplasia in excision margins upon clinical outcome were examined.

RESULTS

Seventy three percent of patients were smokers and 78% consumed alcohol regularly. The majority of lesions were leukoplakias arising in the floor of mouth and ventro-lateral tongue and moderate or severe dysplasia accounted for 86% of histopathological diagnoses. Patient follow up ranged from 24 to 119 months (mean 58 months). Sixty four percent of patients were disease free at most recent clinical follow up, whilst 32% developed local recurrent dysplasia or new site dysplasia with 4% developing oral squamous cell carcinoma (but at sites distinct from their initial OPL). Excision margins were clear in 55% of cases, but 19% showed mild, 21% moderate and 5% severe dysplasia on histopathological examination. No statistically significant associations were seen between patients' age, gender, lesion appearance, site of origin, histopathological grading, presence of dysplasia in resection margins, or alcohol consumption and clinical outcome. Smokers, however, were at significantly higher risk of dysplasia recurrence compared to ex-smokers or non-smokers (P = 0.04).

CONCLUSIONS

In the absence of agreed treatment protocols for OPLs, we recommend CO(2) laser surgery as an effective treatment modality offering precise lesion excision, full histopathological assessment, minimal post-operative morbidity and a 64% disease free clinical outcome. Regular patient follow up is encouraged due to the persistence of field cancerisation effects.

Management of potentially malignant disorders: evidence and critique

At a workshop coordinated by the WHO Collaborating Centre of Oral Cancer and Precancer in the United Kingdom, issues related to management of patients affected by oral leukoplakia were discussed by an expert group. The consensus views of the working group are presented here. Although removal of a lesion still seems to be the predominant method of treatment by the majority of relevant health care professionals, no randomized controlled trials have been undertaken to test the hypothesis that excision either by scalpel or laser greatly influences the potential for later malignant transformation within the oral mucosa of an affected individual. Results of observational studies indicate that, although surgery may have a beneficial effect, this is not likely to reduce the risk of later recurrence nor malignant transformation at the same or another site. Medical measures that lessen the size, extent or histopathological features of dysplasia within leukoplakia likewise presently do not seem to be of particular promise, as relapse or later malignant transformation can occur, and there is a risk of adverse effects, particularly with systemic agents (which themselves may be contra-indicated in some individuals). While the risk of malignant transformation, and the development of further potentially malignant disease may theoretically be reduced by cessation of risk activities, such as tobacco usage and alcohol consumption, there remain no good studies that demonstrate that such measures significantly reduce such events.

[Identification of a recurrent oral squamous cell carcinoma by brush cytology]

BACKGROUND

Large oral lesions comprise the risk that an incisional biopsy does not reveal the most aggressive site in spite of carefully selecting the place of biopsy.

CASE REPORT

The first incisional biopsy of a large, clinically suspect, oral lesion could not identify the subepidermal spread of a recurrent oral squamous cell carcinoma. Atypical cells obtained by a simultaneous brush biopsy prompted a renewed, incisional biopsy which finally established the diagnosis of a recurrent, oral squamous cell carcinoma.

CONCLUSIONS

The presented case emphasizes the value of brush biopsy in the follow-up of oral squamous cell carcinoma, especially in examination of oral lesions covering a large area.

Lasers in surgical periodontics and oral medicine

Surgical lasers rapidly are becoming part of the periodontal armamentarium. This article discusses the different lasers that are suitable for use on the soft tissues of the periodontium. Various laser-assisted periodontal surgical procedures and laser treatment of diseases of the oral mucosa are discussed.

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.

Oral mucosal dysplastic lesions and early squamous cell carcinomas: underdiagnosis from incisional biopsy

OBJECTIVES

To evaluate the degree and causes of underdiagnosis of incisional biopsy in oral potentially malignant lesions (PML).

DESIGN

Cross-sectional retrospective study.

MATERIALS AND METHODS

All pathology slides (incisional biopsy and resection specimen) from 46 patients with oral PML were reviewed and scored blind. The provisional diagnosis was considered in order to provide underdiagnosis or overdiagnosis according to whether this score was lower or higher than the final diagnosis.

MAIN OUTCOME MEASURES

Concordance between the scores for provisional and final diagnoses was compared for reviewed and unreviewed assessments.

RESULTS

Upon review, underdiagnosis significantly decreased from 23.9% to 4.4% (P=0.016, chi-square with the Yates' correction). As the underdiagnosis ratio was not significantly influenced by intra- or inter-observer variability, it is likely to be related to pathologists' interpretation difficulties when examining incisional biopsy specimens.

CONCLUSIONS

The good quality of incisional biopsy samples was demonstrated, but clinicians should be conscious of the possible underdiagnosis by incisional biopsy when planning therapy in suspected early oral squamous cell carcinoma lesions.

Role of lasers and photodynamic therapy in the treatment of cutaneous malignancy

Tumor therapy is not a common indication for the use of lasers, as it is in the treatment of benign vascular skin lesions, since many alternative treatment modalities exist. However, certain patients may benefit from laser therapy of premalignant and malignant skin tumors. Skin tumors can be treated by laser excision, laser coagulation, laser vaporization, or photodynamic therapy (PDT). For these purposes, the carbon dioxide laser, the neodymium:yttrium aluminum garnet laser and the argon laser are particularly suitable. PDT is a therapeutic approach based on the photosensitization of the target tissue by topical or systemic photosensitizers and subsequent irradiation with light from a laser or a lamp inducing cell death via generation of reactive oxygen species. Laser therapy and PDT have shown good results in the curative treatment of actinic keratoses, superficial basal cell carcinoma, Bowen's disease and cheilitis actinica. However, they are not recommended for primary malignant melanoma and invasive squamous cell carcinoma. In some patients, lasers and PDT might also be used effectively for the palliative treatment of cutaneous metastases. In selected patients, lasers and PDT may offer some advantages over routine procedures, e.g. reduction of scarring and better cosmetic results. However, when treating invasive tumors with curative intention, one has to bear in mind the lack of histologic control and the limited depth of tissue penetration of most laser and PDT therapies.

Nd:YAG and CO2 laser therapy of oral mucosal lesions

OBJECTIVE

Experiences gained in the management of oral mucosal lesions by CO2 and Nd:YAG laser therapy in an outpatient clinic treated over an 80-year period are described.

SUMMARY BACKGROUND DATA

Lasers have indications for use in dentistry for incision, excision, and coagulation of intraoral soft tissue. Advances in laser technology have provided delivery systems for site-specific delivery of laser energy with short interaction items on tissue to be ablated. This study retrospectively evaluates a series of clinical case studies.

METHODS

Sixty-four patients with a variety of benign oral soft tissue lesions were treated by laser excision. Thirty-five patients were treated by a pulsed fiberoptic delivered Nd:YAG contact laser, and 29 by a continuous free-beam CO2 non-contact laser. The largest group of lesions treated were leukoplakia (39 cases). Other lesions excised and biopsied were lichen planus, squamous papilloma, pyogenic granuloma, focal melanosis, nonhealing traumatic ulceration, hemangioma, and lymphangioma. All patients were followed postoperatively (mean 6.8 months, range 1-36 months).

RESULTS

Laser excision was well tolerated by patients with no intraoperative or postoperative adverse effects. All patients healed postsurgically with no loss of function.

CONCLUSIONS

CO2 and Nd:YAG lasers are successful surgical options when performing excision of benign intraoral lesions. Advantages of laser therapy include minimal postoperative pain, conservative site-specific minimally invasive surgeries, and elimination of need for sutures.

Positive impact of retinyl palmitate in leukoplakia of the larynx

Laryngeal leukoplakia can be a premalignant precursor of squamous cell carcinoma, is often tobacco-related and can usually be readily monitored by indirect laryngoscopy. One of the main motivations for using retinyl palmitate in patients with persistent leukoplakia was to avoid general anesthesia for elderly patients, who are considered to be high-risk patients when direct larynoscopy is required for possible tissue biopsy. Our study was the first to investigate the effectiveness and toxicity of high-dose retinyl palmitate in the treatment of laryngeal leukoplakia. Treatment was divided into two phases. In the first phase, all patients underwent induction therapy with 300,000 IU/day of retinyl palmitate for the 1st week, which was then adjusted up to 1,500,000 IU/day in the 5th week in patients with resistant lesions. Patients whose lesions progressed during this period were withdrawn from the study. In the second phase, patients whose lesions responded to treatment or remained stable were assigned to a maintenance therapy of 150,000 IU/day. Complete remission was observed in 15 of 20 patients (75% of cases). Partial response was seen in the remaining 5 patients, with 3 of the patients relapsing. The median duration of treatment and follow-up was 18 months (range, 12-24 months). These results indicate that retinyl palmitate has substantial activity in laryngeal leukoplakias. Since only minor side effects were seen, the medication is an excellent candidate as a preventive agent for laryngeal cancer.

Long-term follow-up of larynx leukoplakia under treatment with retinyl palmitate

BACKGROUND

Larynx leukoplakia can be a premalignant precursor of squamous cell carcinoma, is often tobacco related, and can be monitored easily by indirect laryngoscopy. One of the main motivations for using retinyl palmitate in patients with larynx leukoplakia was to avoid general anesthesia for the elderly patients, who are considered to be at high risk for undergoing direct laryngoscopy. Our study investigates for the first time the effectiveness and toxicity of high-dose retinyl palmitate in the treatment of larynx leukoplakia.

METHODS

Treatment was divided into two phases. In the first phase, all patients underwent induction therapy with a high-dose of retinyl palmitate (A-Mulsin Hochkonzentrat, Mucos Pharma, Geretsried, Germany) with 300,000 IU/day for the first week and up to 1,500,000 IU/day, in patients with resistant lesions, in the fifth week. Patients whose lesions progressed during this period were withdrawn from the study. In the second phase, patients whose lesions responded to treatment or remained stable were then assigned to a maintenance therapy of 150,000 IU/day.

RESULTS

We observed a complete remission rate of 75% (15 of 20 patients). Among the 5 patients with partial response, 3 relapsed. The median duration of treatment and follow up was 18 months (range 12-24 months).

CONCLUSIONS

These results indicate that retinyl palmitate has substantial activity in larynx leukoplakias. Furthermore, only minor side effects make it an excellent candidate as a preventive agent for larynx cancer.

Lasers in dentistry: comparing wavelengths

Confusion exists about the wavelengths marketed for dental use. General properties of lasers, laser/tissue interactions and clinical applications of three wavelengths are examined.

Risk of preneoplastic and neoplastic events in operated oral leukoplakias

We retrospectively analysed 167 consecutive patients with oral leukoplakias operated on by CO2 laser resection in the Day Hospital of the Istituto Nazionale Tumori in Milan from January 1981 to December 1988, with post-operative histological examination negative for cancer. Within 5 years there were 69 patients with at least one unfavourable event. First unfavourable events were: 31 local relapses, 27 new leukoplakias, 5 oral carcinomas and 6 other neoplasms elsewhere. To identify possible prognostic factors we recorded age, sex and history of previous oral leukoplakias or head and neck cancers; also number, site, size and type of lesion; as well as tobacco and alcohol consumption and oral hygiene. The Cox regression model was employed to compare disease-free survival between different patient groups, both by univariate and multivariate analysis. From this analysis it emerges that age of operated patients and size of resected lesion are significantly predictive for development of relapses, new leukoplakias and carcinomas.

Prevention of local relapses and new localisations of oral leukoplakias with the synthetic retinoid fenretinide (4-HPR). Preliminary results

This paper analyses preliminary results of a randomised chemoprevention trial in patients surgically treated for oral leukoplakia started in 1988 at the Istituto Nazionale Tumori of Milan with the synthetic retinoid N-(4-hydroxyphenyl)-retinamide (4-HPR). To date 115 patients have been randomised, after surgical excision of oral leukoplakia, to receive 200 mg 4-HPR daily for 52 weeks versus no intervention. 80 patients completed the 1-year intervention, 41 in the control group and 39 in the 4-HPR group. During this period 12 local relapses or new lesions occurred in the control group and three in the 4-HPR group. Only 5 patients interrupted the intervention because of toxicity. No impaired dark adaptation was observed. It is concluded that 4-HPR is well tolerated and seems efficacious in preventing relapses and new localisations during the treatment period. This promising trend needs further confirmation.

Immediate biopsy versus a therapeutic trial in the diagnosis and treatment of vesiculobullous/vesiculoerosive oral lesions. Opposing viewpoints presented

There are at least two treatment strategies in the diagnosis and treatment of oral vesiculobullous/vesiculoerosive disease. The relative merits of immediate biopsy and initial therapeutic trial regimens are debated.

Minimizing risk of infection using a carbon dioxide laser

The carbon dioxide laser is a surgical device increasingly important to dentistry. The advantages of laser use in the treatment of oral disease have been well documented. Such benefits include bloodless incisions, accurate tissue destruction, reduced pain, minimal swelling, excellent hemostasis, and limited postoperative tissue morbidity. Little information exists currently regarding laser use in the management of medically complex patients, most notably patients with infectious diseases. This article reports the use of the carbon dioxide laser for reducing the risks of disease transmission in the surgical management of an human immunodeficiency virus (HIV) seropositive patient.