In such cases of physical diseases, I would rather work with prayers than spell casting.
Praying can be a very useful simple method of bringing hope and goodness to one's life by doing very straightforward things, which eventually might help a lot and bring benevolence.
I know that it gives you no guarantee to fully cure the people you love physically or medically, however prior is a very significant religious work which in many cases brings hope and lightens up myriads of ways.
Praying, can be a very strong action you may do by any method you choose, any time of the day.
Also, as Lark said, medically taking care of things that are physical and trying to do the best to stay healthy is the most vital thing which can be done here.