Search

Background: Photodynamic therapy with aminolevulinic acid (ALA PDT) for oral leukoplakia has shown promising effects in regression of oral leukoplakia. Although ALA has been extensively studied and is an ideal photosensitizer, the optimal light dose for treatment of oral leukoplakia has not been determined. We conducted a phase I study to determine MTD and DLT of PDT in patients treated with ALA for leukoplakia., Methods: Patients with histologically confirmed oral leukoplakia received a single treatment of ALA PDT in cohorts with escalating doses of light (585nm). Clinical, histologic, and biologic markers were assessed., Results: Analysis of 11 participants is reported. No significant toxicity from ALA PDT was observed in patients who received ALA with a light dose of up to 4J/cm(2). One participant experienced transient grade 3 transaminase elevation due to ALA. One participant had a partial clinical response 3months after treatment. Biologic mucosal risk markers showed no significant associations. Determination of MTD could not be accomplished within a feasible timeframe for completion of the study., Conclusions: ALA PDT could be safely administered with a light dose up to 4J/cm(2) and demonstrated activity. Larger studies are needed to fully elucidate the MTD and efficacy of ALA-PDT., (Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This study evaluates the efficacy of lycopene in the treatment of oral leukoplakia and compares two different doses with a placebo. Fifty-eight clinically and histologically diagnosed patients of oral leukoplakia were selected for the study. They were randomly divided into three groups. Group A: (n = 20; 8 mg lycopene/day), Group B: (n = 20; 4 mg lycopene/day) and Group C: (n = 18; placebo). The duration of the therapy was three months. Outcome was assessed clinically as well as histologically. Post-treatment patients were on follow-up for two months. Student's 't' test was used for statistical evaluation. Clinically the patients in Groups A, B, C had a mean response of 80%, 66.25% and 12.5% respectively. Histological evaluation too had similar results. Patients receiving lycopene in both regimes show highly significant difference in response as compared to placebo (Group C). The observed effect of lycopene suggests that it can be effectively and safely used for the management of oral leukoplakia.

Given the increase in the age distribution of the population, an increase in cancer incidence rates are to be expected. Oral cancer is a disfiguring disease that continues to increase in incidence, particularly in the young, and to an extent that cannot be fully explained by increased exposure to known risk factors. Despite extensive research on treatment modalities towards oral cancer, the 5-year survival rate of this disease has not been improved over the last 4-5 decades. These facts strongly favour chemoprevention-systemic medication to revert, stop, or delay the carcinogenic process-as an approach to treating oral cancer. A chemopreventive approach to oral cancer most likely should encompass a combination of drugs targeting metabolic pathways relevant to oral carcinogenesis. Candidate drugs are retinoids and selective inhibitors of cyclooxygenase-2, epidermal growth factor receptor (EGFR), and peroxisome proliferator activated receptors (PPARs). Chemopreventive trials so far have used surrogate intermediate biomarkers as measurement of treatment effect. However, the efficiency of any drug for chemopreventive use should be assessed through a prospective randomized trial and evaluated by the only definitive end point for prevention of cancer, the incidence rates of new carcinomas.

Retinoids are the natural and synthetic derivatives of vitamin A. Epidemiological studies indicate that a low intake of vitamin A is associated with an increased risk of squamous cancer. In vitro studies on cancer cells show that exposure to retinoids results in the inhibition of growth, by blocking the cell cycle or by inducing apoptosis. With respect to the clinical efficacy of retinoids some positive effects have been observed in early stage oral and oropharyngeal cancer. Administration of retinoids has been shown to elicit responses in leukoplakia, a premalignant lesion of the oral mucosa that frequently develops into invasive cancer. Furthermore, it has been possible with a retinoid, 13-cis-retinoic acid, to delay or inhibit the development of second primary tumors in patients who have been curatively treated for a first primary tumor in the oral cavity or oropharynx. Recent trials, however, failed to show protective effects on the development of second primary tumors. Because of the short duration of the response, the intrinsic resistance to retinoids and the toxic side effects, the treatment with this class of compounds has not become a standard therapy. Recent studies have shed light on how preneoplastic and neoplastic cells defend themselves against the growth inhibiting action of retinoids. An increased retinoid breakdown and an inactivation of nuclear retinoid receptor appear to be the cause of acquired or intrinsic resistance. This knowledge can be used to develop novel tumor-selective strategies. This review gives an update on the role of retinoids in oral and oropharyngeal cancer and their precursor lesions. The focus will be on the anticancer activity, the mechanism of action and future directions.

In a double-blind study 10 patients with oral leukoplakia were treated daily (three topical applications) with 0.1% isotretinoin gel or a placebo for 4 months. Nine patients completed the treatment, while one patient was lost to follow-up. Subsequently, the patients who had received the placebo used the active medication for an additional 4 months. All patients treated with the active medication showed a significant improvement of the oral lesions while, in the patients receiving only the placebo, the size of the lesions remained the same. Also the group of patients who received the active medication after the placebo showed an improvement in the size and clinical appearance of the lesions. A complete response was defined as the complete disappearance of the lesion as assessed by visual inspection, while a partial response was defined as a 50% or more reduction in the size of the lesions. In total we had a complete response and eight partial responses. No side-effects from the use of the gel were ever observed. The percentage of bcl-2-positive cells was evaluated in the basal layer from a minimum of 1000 cells in each case and the bcl-2 immunostaining was scored using three groups: - (< or = 10% cells); + (< or = 50% cells); +2 (> or = 50% cells). The presence of apoptotic bodies was evaluated in a random fashion in the parabasal layer in 20 HPF. Immunohistochemical analysis for bcl-2 protein showed that before treatment a weak positivity of the basal layers, with a focal positivity of some parabasal cells, was present: five out of nine specimens were positive. Only a few apoptotic bodies were observed. After treatment in almost all specimens it was possible to observe a complete bcl-2 negativity with a positivity in only one specimen out of nine. An increase in apoptotic bodies was observed. Statistical analysis showed that the difference between the bcl-2 positivity in the two groups was not statistically significant (P = 0.134) while, on the contrary, the difference in the count of the apoptotic bodies between the same two groups was statistically significant (P = 0.0193). In conclusion, the data obtained from this pilot study show that good results can be obtained with the topical use of 13-cis-retinoic acid.

We conducted a double-blind placebo-controlled trial to evaluate the chemopreventive potential of either vitamin A alone or beta carotene alone in subjects with oral leukoplakia in Kerala, India. We randomised 160 fishermen and women with oral precancerous lesions to receive oral vitamin A (retinyl acetate 300,000 IU/week x 12 months, n = 50), or beta carotene (360 mg/week x 12 months, n = 55), or placebo (n = 55). Blood, saliva and urine samples were collected at baseline and at exit to study serum micronutrients and mutagenicity assays. Biopsies of the mucosal lesions at entry were performed for histopathological exclusion of malignancy. The subjects were examined once every 2 months to establish clinical response of lesions and toxicity, if any. The results are based on 43 complaint subjects on placebo, 42 on vitamin A and 46 on beta carotene. The complete regression rates were: 10% in the placebo arm, 52% with vitamin A and 33% with beta carotene (P < 0.0001). Homogeneous leukoplakias and smaller lesions responded better than non-homogeneous and larger lesions. No major toxicities were observed. Half of the responders with beta carotene and two thirds with vitamin A relapsed after stopping supplementation. Serum beta carotene concentration increased substantially with beta carotene administration while with vitamin A supplementation there was no change in serum retinol levels. In the vitamin A treated group there was a significant decrease in serum alpha tocopherol. Vitamin A administration resulted in a significant remission of oral leukoplakia without any side effects of prolonged vitamin A supplementation. The results of this study, as well as those from previous studies, appear to provide strong supporting evidence to justify long term trials with vitamin A in subjects with high-risk leukoplakias with oral cancer as an endpoint.