Not sure what to write...

Have discovered today that an old friend has been diagnosed with Breast Cancer and is having surgery etc in February, it seems to me that more and more people I know have had, are recovering from or just diagnosed with some form of cancer. All I can do is pray as I have and still do for others, but feel quite useless and unsure of what to say to her. My prayer list of people who are ill, undergoing medical treatment or recovering seems to be growing ever longer and my prayers more desperate. How as Christians are we to respond to this seeming increase of illness, disease and bad health around us??? I am at a loss for more to say.