During the fight against cancer cells our body produces special enzymes, called phase 2 enzymes. Sulforaphane is a phase 2 enzyme inducer, thereby neutralizing carcinogens before they can damage DNA. Sulforaphane inhibits benzo[a]pyrene-DNA and 1,6-dinitropyrene-DNA adducts formation. A study by James D. Brooks et al entitled Potent Induction of Phase 2 Enzymes in Human Prostate Cells by Sulforaphane has shown that sulforaphane induces phase 2 enzyme expression and activity in human prostate cells . This study may help to explain the lower prostate cancer risk with men who consume more cruciferous vegetables.
A team of scientists lead by B. Abbouit at the Ohio State University investigated the effect of isothiocyanates (sulforaphane and erucin) in primary or secondary bladder cancer prevention. Both phytochemicals showed inhibition of bladder cancer cells, which was associated downregulation of survivin, epidermal growth factor receptor and human epidermal growth factor receptor 2 and apoptosis.
A 2012 study by the Texas Children's Hospital suggested a potential role of sulforaphane as an adjunctive agent to improve the therapeutic response in acute lymphoblastic leukemia patients . This type of cancer is the most common hematological cancer in children. The scientists found that purified sulforaphane had anticancer properties in a broad range of leukemic cells. More specifically they found that sulforaphane caused dose-dependent apoptosis and cell cycle arrest, mainly by activation of caspases. While sulforaphane killed cancer cells, it did not affect healthy cells. It should be noted that the levels of sulforaphane used in this study were quite high and can not be obtained by eating cruciferous vegetables, such as broccoli.
 Potent induction of phase-2-enzymes in human prostate cells by sulforaphane.. Cancer Epidemiology Biomarkers and Prevention, Vol. 10, 949-954, September 2001
 Inhibition of bladder cancer by broccoli isothiocyanates sulforaphane and erucin: characterization, metabolism, and interconversion. Mol Nutr Food Res. 2012 Nov;56(11):1675-87
 Sulforaphane induces cell cycle arrest and apoptosis in acute lymphoblastic leukemia cells. PLoS One. 2012;7(12):e51251