BACKGROUND
Oral leukoplakia is an important model for developing chemoprevention approaches for lesions in the upper aerodigestive tract. These lesions most often result from exposure to carcinogens such as tobacco and alcohol and may precede development of invasive cancer. The potent antioxidant alpha-tocopherol (vitamin E) has prevented the development of cancers of the oral cavities in animal models.
PURPOSE
The objectives of this study were to evaluate the toxicity and efficacy of alpha-tocopherol in patients with oral leukoplakia and to assess the feasibility of performing chemoprevention trials through the network of the Community Clinical Oncology Program (CCOP).
METHODS
A single-arm phase II study using the nontoxic agent alpha-tocopherol to treat oral premalignant leukoplakia was performed at seven institutions affiliated with the CCOP through The University of Texas M. D. Anderson Cancer Center. Patients with symptomatic leukoplakia or dysplasia were treated orally with alpha-tocopherol (400 IU) twice daily for 24 weeks. Follow-up was performed at 6, 12, and 24 weeks after the start of treatment to assess toxicity and response, and serum alpha-tocopherol levels were determined at baseline and at 6 and 24 weeks.
RESULTS
Of the 43 patients who have completed 24 weeks of treatment, 20 (46%) had clinical responses and nine (21%) had histologic responses. Mean serum alpha-tocopherol levels were 16.1 micrograms/mL at baseline and increased to 34.29 micrograms/mL after 24 weeks of treatment. Patient-recorded drug calendars, as well as serum drug levels, indicated excellent patient compliance; an average of 95% of the prescribed pills were taken. Treatment was extremely well tolerated; no grade 3 or 4 toxic effects were reported.
CONCLUSIONS
Administration of alpha-tocopherol resulted in both clinical and histologic responses in premalignant leukoplakia lesions. The study also demonstrated that chemoprevention trials can be performed through the CCOP. The major problems were that a high percentage of patients were not assessable for response, some patients withdrew because expenses were not reimbursable, and there was limited participation within the CCOP network. These problems may reflect difficulties inherent in the implementation of multi-institutional chemoprevention trials.
IMPLICATIONS
The efficacy of alpha-tocopherol alone and in combination with other chemopreventive agents for carcinogenesis in the upper aerodigestive tract should be explored in future trials.