Stopping cancer treatments is a very personal decision that you will have to make. You will want to consider the feelings of your closest family, but ultimately you have to decide.
Most people think about their quality of life. If you are extremely sick, weak, and in pain during treatment or despite treatment, and you are not feeling well enough to enjoy seeing your family or friends, that might be when you start to think about stopping cancer treatment.
When you got your cancer diagnosis, at some point you may have thought that you wanted to live long enough to see certain people, or certain events, like the upcoming birth of a grandchild, or a wedding or graduation. If you have done the things you wanted to do, and your quality of life is not good, that is another time you might think of stopping the treatment.
If your cancer has not responded, or it has recurred, and the treatment took a toll on you that you don’t want to repeat, that might be a time you want to think about not starting a new round of chemotherapy.
Deciding to stop the cancer treatment does not mean you stop supportive care. You can still get pain medicine, other related treatments, and oxygen to help breathing. Anything you need that can make you feel more comfortable should be continued.
Stop Cancer Treatment
“If you have had three different treatments and your cancer has grown or spread, more treatment usually will not help you feel better or increase your chance of living longer. Instead, more treatment could cause serious side effects that shorten your life and reduce the quality of the time you have left.”
“You don’t have to have treatment. Some people choose not to have treatment at all. People with very advanced cancers sometimes find they’d rather treat the pain and other side effects of their cancer so that they can make the best of the time they have remaining.” 
“If your doctor approaches you about ending your cancer treatment, you might feel betrayed. You might feel like your doctor wants to give up on you. Maybe you’ve been denying the fact that your cancer treatment isn’t working, and you aren’t ready to accept the fact that it might be time to stop.” 
“There are times when you and the person with cancer will not agree on decisions that are made. One of those times may be when they decide that treatment aimed at fighting the cancer is no longer worth the physical and emotional cost – they want to let the disease run its course. You may feel like they’re giving up, and that can be very upsetting and frustrating. You may feel sad or angry that they have decided not to seek further treatment.” 
“Many chemotherapy agents have been tested in patients with mesothelioma. While some have performed effectively, proving their effectiveness has been difficult largely due to the number of patients required for statistically significant results. Because the disease is so rare, mesothelioma trials have historically been small in size. This has contributed to the widespread belief that mesothelioma is not treatable.” 
 Mayo Foundation for Medical Education and Research
 Riverside Health System