3,3-Diindolylmethane (DIM): a nutritional intervention and its impact on breast density in healthy BRCA carriers. A prospective clinical trial.
Level 3 - non-randomized controlled study
Prospective non-randomized study with a matched untreated control group.
PubMed 32458980 · doi:10.1093/carcin/bgaa050
What was done
In a prospective single-arm study with a matched comparison group, 23 healthy female BRCA carriers (median age 47 years; 78% postmenopausal) received oral 3,3-diindolylmethane (DIM) 100 mg once daily for 1 year. The amount of fibroglandular tissue (FGT) and background parenchymal enhancement (BPE) on breast MRI before and after intervention were scored by two independent radiologists using the BI-RADS system. Serum estradiol and testosterone levels were also measured, and MRI changes were compared with a parallel group of age- and menopausal-status-matched untreated BRCA carriers.
What was found
In the DIM group, average FGT score decreased from 2.8 ± 0.8 at baseline to 2.65 ± 0.84 after 1 year (P = 0.031), with no significant change in BPE (P = 0.429). The matched untreated control group showed no significant change in FGT (P = 0.33) or BPE (P = 0.814) over a parallel year. Mean estradiol decreased from 159 to 102 pmol/l (P = 0.01), and mean testosterone decreased from 0.42 to 0.31 pmol/l (P = 0.007). Side effects were reported as grade 1.
Why it matters
This study provides preliminary human evidence that oral DIM supplementation may modestly decrease MRI-measured fibroglandular tissue density and circulating sex hormone levels in BRCA mutation carriers.
Limits
The sample size was very small (n=23 treated), allocation was not randomized, and the exact number of control participants was not reported in the abstract. Breast density is a surrogate biomarker rather than a direct clinical cancer endpoint.
Cited by
- supports Diindolylmethane (DIM) can inhibit or lower estrogen levels.