Glutathione (GSH) concentration is high in most cancer cells and this may be an important factor in resistance to chemotherapy.  Several studies have shown that  whey protein concentrate paradoxically might deplete tumor cells of GSH, making them more susceptible to chemotherapy while inhibiting a wide range of free radicals in normal cells.  Taking whey protein boosts your red and white blood cells and hemoglobin levels, making it easier to tolerate chemo and fight off cancer.  Since it is a highly bioactive protein it also directly enhances immune function. 

There are really no downsides to this approach and the cost is modest.  Make sure that the brand you pick does not contain refined sugars and that it is "cold processed" which avoids "denaturation" of the protein that reduces its biological activity and  effectiveness.  The dose?  Given the presence of cancer, approximately 30 grams, several times a day is reasonable.  Add it to a shake or smoothie or other foods.