The retinoids studied are not effective in causing regression of CIN3 but may have some effect on CIN2. The data on CIN1 are inadequate. Retinoids are not effective in preventing progression of CIN of any grade. At the doses given for the duration of treatment studied, the retinoids were reasonably well tolerated.
Low-dose topical delivery of all-trans retinoic acid for cervical intraepithelial neoplasia II and III.
The objective of this study was to determine an effective dose for all-trans retinoic acid (atRA) delivered with a cervical cap and sponge for 4 days to women with cervical intraepithelial neoplasia (CIN) II/III.
                Study participants made up of 175 women with biopsy-proven CIN II/III were randomized to four consecutive days of atRA at one of three doses (0.16%, 0.28%, and 0.36%) or placebo. All subjects underwent a repeat colposcopy evaluation and biopsy of the cervix at 12 weeks.
                The study participants mean ages were 27.6 years. The racial distribution was 63% Caucasian, 27% African American, and 8% other. Among participants, 93% were human papillomavirus-positive at baseline with 68% positive for high-risk types. The disease response at 12 weeks to atRA or placebo was not significantly different (P = 0.49) among the four dose groups. Participants with CIN II at baseline were more likely to be free of disease at 12 weeks than participants with CIN III at baseline (P = 0.003). There were no reported systemic adverse events related to drug or placebo exposure and only mild local self-reported and clinician-detected toxicities.
                Lower concentrations of atRA applied with a cervical cap for 4 days were no more effective than placebo. However, the rate of histologic regression in biopsied CIN II/III patients was high even over a short time interval, and emphasizes the importance of having a placebo arm and an adequate sample size.