The purpose of hGH is replacement of existing hGH levels - at least from the anti-aging standpoint. There is really nothing else like it. IGF-1 peptide is considered a peptide-based replacement, however it is still supplementing the chain that is ultimately hGH, so I couldn't tell you what that does to cancer. The primary concern w/ breast cancer is presence of extra estrogen that promotes the tumors. Beyond that you'd need to do more research.