What are the issues related to medical treatment that prolongs life of questionable quality?

While reading an answer to [How to overcome the suffering of attachement to the body's continued existence (in Western modernity)?](https://buddhism.stackexchange.com/a/13802/57) , I began to wonder about a related matter. In the answer: >In preparation for death you should: 1) accept the fact everyone must die and let go of the fear of death OK, but how about this situation: Let's say I have terminal cancer, and the doctor says I will only live another 6 months. However, if I get some difficult treatment (let's say chemotherapy that often causes severe pain), I may live up to 10 years longer. So from a Buddhism point of view: 1) Would there be any concern if I didn't get any treatment? It isn't suicide, but I am not taking an action will hasten death. 2) Would there be any concern if I did get the treatment? Does that imply a fear of death, by postponing the inevitable? And since a goal of Buddhism is to reduce suffering, while understanding pain can be managed, can voluntarily increasing ones suffering be justified? In each case, is there any impact on karma looking to the next rebirth? Finally, I am not referring to medical treatment in general. Only when it is very invasive and severely impacts ones normal life (and lifespan).