OBJECTIVES: I. Compare the efficacy of eflornithine versus placebo in causing regression in patients with cervical intraepithelial neoplasia. II. Compare the qualitative and quantitative toxicities of these treatment regimens in these patients. III. Establish the biochemical tissue markers of DNA content, PCNA, the ras oncogene, EGFR, and keratin and involucrin as intermediate biomarker end points for squamous carcinogenesis in these patients.