Oral diindolylmethane (DIM): pilot evaluation of a nonsurgical treatment for cervical dysplasia

Standard surgical treatment for CIN may impair fertility generating a need for alternative treatment options. We tested the efficacy and toxicity of oral DIM in the treatment of CIN 2 or 3 lesions.

Patients with biopsy-proven cervical intraepithelial neoplasia (CIN) 2 or 3 scheduled for loop electrosurgical excision procedure (LEEP) were randomized 2:1 to receive diindolylmethane (DIM) (BioResponse-DIM, BioResponse, Boulder, CO) orally at approximately 2 mg/kg/day for 12 weeks or placebo (defatted rice bran, BioResponse). Subjects were evaluated every 3-4 months for 1 year. Analysis of data up to 1 year was assessed including Pap smear, HPV, colposcopy, biopsy and physical examination were performed at follow-up. Central pathology review confirmed all histology diagnoses.

To date, 64 subjects (mean age 28 years, range 18-61) have been enrolled (45 in the DIM arm, 19 in the placebo arm), with 60 available for analysis. Average follow-up was 6 months. At enrollment, 58% were diagnosed with CIN 2 and 42% with CIN 3, 57% of subjects were Caucasian, 15% African American, 12% Hispanic and 17% Asian. During treatment 2 subjects (3%) complained of nausea (grade 2) at the 3- to 4-month visit. No systemic toxicities were observed (normal CBC, LFTs, comprehensive metabolic). Forty-six subjects had biopsies at first follow-up (77%). Twenty-one subjects (47%) in the DIM group had improved CIN with a decrease by 1-2 grades or a normal result. Median time to improvement was 5 months. Improved Pap smear was seen in 49% (22/45) with either a less severe abnormality or normal result. Colposcopy improved in twenty-five subjects in the DIM group (56%). Of these 25 subjects, 21 (84%) had improved colposcopic impression, 13 (52%) had a decrease in involved quadrants and 18 (72%) had a decrease in lesion number. Complete colposcopic response was observed in 4 subjects (9%). Stratifying by level of dysplasia, age, race, HPV status, tobacco use, contraceptive used did not alter the results. At median follow-up of 6 months, 85% of subjects have not required LEEP based on routine clinical triage of improving global assessment. There was no statistically significant difference in any outcome between the DIM and placebo group.

Oral DIM at 2 mg/kg/day is well tolerated with no significant toxicity. We observed a high rate of clinically significant improvement in confirmed CIN 2 or 3 lesions among both treatment groups in this randomized clinical trial.