Prostate Cancer: Why Cruciferous Vegetables
Cruciferous or Brassica vegetables, such as broccoli, cauliflower, Brussels sprouts, cabbage, bok choy, collard greens, and kale, are rich in sulforaphane and indole-3 carbinol (I3C) (Higdon et al. 2007).
Sulforophane and I3C are the two best known plant chemicals that offer the most fighting cancer benefit. I3C is converted by the body to 3’3 Diindolymethane (DIM) which is the compound that has the anti-cancer benefits.
These phytochemicals (plant chemicals) possess anti-carcinogenic properties, such as halting progression of cancer cells (cell cycle arrest), inhibition of tumor invasion and angiogenesis, anti-inflammatory activity, inhibition of extracellular signal-regulated kinases, proteasome degradation, and alteration of phase I and phase II biotransformation enzyme expression (Krystal et al, & Singh et al. 2005).
Sulforaphane has also been shown to induce apoptosis (cancer cell death) in prostate cancer cells in vitro and in vivo (Choi et al 2005) and I3C has anti-proliferative and anti-metastatic properties in animal models of CaP once converted to DIM (Garikapaty et al. 2005).
A preliminary study of men newly diagnosed with prostate cancer showed a 41% decreased risk of prostate cancer among men eating three or more servings of cruciferous vegetables per week, compared with those eating less than one serving per week  Protective effects of cruciferous vegetables were thought to be due to their high concentration of the carotenoids, lutein and zeaxanthin, as well as their stimulatory effects on the breakdown of environmental carcinogens associated with prostate cancer(Cohen et al. 2000). 
What should you do?
Consume 5 to 10 servings of a variety crucifers a week. Good quality supplementation that includes broccoli extracts (sulforophane) and DIM can be helpful as well.
Reference:
Higdon, J. V., Delage, B., Williams, D. E., Dashwood, R. H., Cruciferous vegetables and human cancer risk: Epidemio- logic evidence and mechanistic basis, Pharmacol. Res. 2007, 55, 224 – 236.
Kristal, A. R., Lampe, J. W., Brassica vegetables and prostate cancer risk: A review of the epidemiological evidence, Nutr.
Singh, S. V., Srivastava, S. K., Choi, S., Lew, K. L., et al., Sulforaphane-induced cell death in human prostate cancer cells is initiated by reactive oxygen species, J. Biol. Chem. 2005, 280, 19911 – 19924.
Choi, S., Lew, K. L., Xiao, H., Herman-Antosiewicz, A., et al., D,L-Sulforaphane-induced cell death in human prostate cancer cells is regulated by inhibitor of apoptosis family pro- teins and Apaf-1, Carcinogenesis 2007, 28, 151 – 162.
Garikapaty, V. P., Ashok, B. T., Chen, Y. G., Mittelman, A., et al., Anti-carcinogenic and anti-metastatic properties of indole-3-carbinol in prostate cancer, Oncol. Rep. 2005, 13, 89–93.
Cohen JH, Kristal AR, Stanford JL. Fruit and vegetable intakes and prostate cancer risk. J Natl Cancer Inst 2000;92(1):61–8.
Parsons JK, Newman V, Mohler JL, Pierce JP, Paskett E and Marshall J: The Men’s Eating and Living (MEAL) study: a cancer and leukemia group B pilot trial of dietary interven- tion for the treatment of prostate cancer. Urology 2008