I assume that you meant that they were previously 3C and are now stage 4???
There is no fixed answer, many factors play into effect.
First and most important is an alkalyzing diet and avoiding any and all sugars or artificial sweeteners. Stevia is safe from what I have seen.
As mentioned in other posts, Essiac Tea has tremendous health benefits. This helps with alkalyzing and has many other health benefits.
Cesium Chloride is probably the best hope if they are terminal and I think even if not. There are significant risks of course.
Large doses of vitamin C are tremendously helpful also large doses of certain B vitamins, E, and Co-Q10 really make a difference.
Minerals such as selenium, calcium, magnesium, etc have definite benefits.
My wife was told that within 30 days she would lapse into a coma and die. With help from alkalyzing, herbals, minerals, and vitamins, she far outlived even the best prognosis offered and did not suffer the horrors of Chemo-therapy.