Venom is amazing stuff. It can kill in many different ways, depending on the type of venom. It also can be used to heal. As I recall, our best anti-coagulants were derived from a venom that prevents blood from clotting. For example.
Well, a scorpion venom shows promise in treat breast cancer.
There are many, many substances that kill breast cancer cells in vitro but fail in vivo for many reasons (including toxicity when administered systemically to living patients).
Don’t get excited about any cancer treatment until it has been tested in large groups of actual patients – large enough for statistical analysis.