@prarysky
This is what I see on line:
"So far, no studies have shown that taking collagen supplements raises your risk of breast cancer. Collagen from supplements is broken down during digestion, so it doesn’t act like the collagen that’s already in your breast tissue. Cancer research has found that collagen in the body plays a role in how cancer cells grow and spread to other organs. However, researchers haven’t studied how taking a collagen supplement might affect breast cancer. Until more research is done, we don’t know how collagen supplements might affect breast cancer."

Even in animal studies no studies have looked at collagen supplements and their relationship to breast cancers.

But...out of an abundance of caution some doctors do not recommend collagen supplements. A program like cronometer would help to monitor your diet to see if you are consuming enough nutrition to maintain collagen. Of course it cannot screen for age and other problems that would lower collagen production which the body does naturally.