Sulforaphane is obtained from cruciferous vegetables, such as broccoli. It is necessary to have enzymatic production of sulforaphane, which is generated when myrosinase converts glucoraphanin into sulforaphane. So, when you are looking for this as a supplement, you will want the activated form. Castro, et al. published a study in Cancer Prev Res, March 2019 that reported sulforaphane suppressed breast cancer stem cells. In regards to sulforaphane there may be some contradicting aspects when it comes to the immune response. Some studies suggest it inhibits TGF-B, which can reduce immune suppression in advanced cancers. A study by Johler, et al., Cancer Immunol Immunother, Dec 2016 showed that sulforaphane inhibits macrophage migration inhibitory factor (MIF) that can help cancer escape the immune system. Also, inhibiting MIF with sulforaphane can result in a decrease in MDSCs, which should further help the anti-cancer immune response. However, the authors, Liang, et al. published a study in AdvBiolRegul, Jan 2019 discussing how sulforaphane may be a “doubled-edged sword” when it comes to cancer immunotherapy. They state that sulforaphane acts pro-oxidatively in human T cells, which can inhibit their activation and tumor killing functions. Clearly, it is hard to say if it is best to take the good with the bad in regards to sulforaphane. In general, I feel the benefits mayoutweigh the negatives, but we certainly need more studies.