Cancer is often a disease that lasts a long time, and people may be treated for it for many years. Sometimes, people close to the patient who were very involved at first grow distant as the treatment continues over the course of months or years. It is understandable that you can become "burned out" when supporting a person with cancer. Still, people with cancer need emotional support throughout the entire course of the illness. Remember that the encouragement and support of those around them can help people with cancer get a new perspective and have hope, even when they feel beaten down by cancer or its treatment. Also, the support of family and friends helps people with cancer try to get on with their old activities and have as normal a life as their illness will allow. So if you are going to be a support for a person with cancer, try to hang in there for the long term. Being there and then leaving can be very painful for your loved one, and can feel even worse than not ever being there at all.

It is often hard to know if you are crossing boundaries or treating the person with cancer too much like a "cancer patient" and not like your friend or family member. Encourage the person with cancer to let you know if you cross this line. Every person with cancer appreciates the friend or family member who remembers that they used to be a person without cancer -- that they had, and still have, strengths and weaknesses, interests, and parts of life that have nothing to do with cancer. Sometimes being the person in the "cancer patient's" life who remembers the whole person is a special gift.

http://www.cancer.org/Treatment/UnderstandingYourDiagnosis/TalkingaboutCancer/ListenwithYourHeart/listen-with-your-heart-living-with-cancer