Effect of diindolylmethane supplementation on low-grade cervical cytological abnormalities: double-blind, randomised, controlled trial

Br J Cancer. 2012 Jan 3;106(1):45-52. doi: 10.1038/bjc.2011.496. Epub 2011 Nov 10.

Abstract

Background: Cervical screening identifies many women with low-grade abnormalities. In vitro and in vivo studies have shown that diindolylmethane (DIM) could potentially halt (cervical) carcinogenesis. We report on a randomised controlled trial of the effect of DIM in women with low-grade cervical cytological abnormalities.

Methods: We conducted a pragmatic double-blind, randomised controlled trial of 150 mg DIM (from BioResponse DIM) or placebo daily for 6 months in women with newly diagnosed, low-grade cytological abnormalities. Randomisation was in the ratio 2 (DIM) to 1 (placebo). All women were invited for colposcopy at 6 months with biopsy of any abnormality.

Results: Of the 551 randomised women available for analysis, 9% on DIM and 12% on placebo had cervical intraepithelial neoplasia-2 (CIN2) or worse after 6-month supplementation (risk ratio (RR) 0.7 (95% confidence interval (CI): 0.4-1.2)), whereas 4.6% and 5.1%, respectively, had CIN3 or worse (RR 0.9 (95% CI: 0.4-2.0)). A total of 27.3% of women on DIM and 34.3% on placebo had no sign of disease (negative cytology, colposcopy and human papilloma virus (HPV) tests) at 6 months (RR 0.8 (95% CI: 0.6-1.0)). Of those HPV-positive at baseline, 69% (114 out of 166) of the DIM group were positive at 6 months compared with 61% (43 out of 71) of the placebo group: RR 1.1 (95% CI: 0.9-1.4). Diindolylmethane supplementation was well tolerated.

Conclusion: The results suggest that short-term DIM supplementation (150 mg day(-1)) is well tolerated, but is unlikely to have an effect on cytology or HPV infection. Uncertainty remains regarding its effect on CIN2+.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alphapapillomavirus / isolation & purification
  • Anticarcinogenic Agents / adverse effects
  • Anticarcinogenic Agents / pharmacology
  • Anticarcinogenic Agents / therapeutic use*
  • Apoptosis / drug effects
  • Cervical Intraepithelial Neoplasia / drug therapy*
  • Cervical Intraepithelial Neoplasia / virology
  • Double-Blind Method
  • Female
  • Humans
  • Indoles / adverse effects
  • Indoles / pharmacology
  • Indoles / therapeutic use*
  • Middle Aged
  • Placebos
  • Uterine Cervical Neoplasms / prevention & control

Substances

  • Anticarcinogenic Agents
  • Indoles
  • Placebos
  • 3,3'-diindolylmethane