One of the defining characteristics of a cancerous mass is that it grows faster than the healthy tissues around it. The only way it can do that is by stealing n

One of the defining characteristics of a cancerous mass is that it grows faster than the healthy tissues around it. The only way it can do that is by stealing nutrients that would otherwise have gone to nourish those health tissues. Cancer is very good at getting food from the body. That's why it can grow so well, and that's why many cancer patients lose weight as their cancer advances. It's really not possible to simply remove a cancer's source of food... not without killing the patient. Cancer's source of food is the patient's source of food, and if that is not available, the patient themselves becomes cancer's source of food. Like any other tissues, cancers may respond to hormones, and in some cases hormones can be used to affect a cancer's growth. Hormones are not "food," but chemicals that affect the operations of cells. Radiation is never preventative; it is a targeted therapy for killing cancer cells. They only give it to people who have cancer and really need it. I would think of it as an integral and important part of your friend's treatment.