If i decide not to get treatment for my stage 4 lung cancer, how long am i likely to live?

Average 4-6 months: The average survival for patients with stage 4 lung cancer is usually 4-6 months if only supportive therapy is used. Survival will depend on subtype of lung cancer; areas of cancer spread specially critical organs (brain, liver); and also overall patient health. Rarely, some patients can have longer survial of upto a year.

Integrated Care Matt: Most lung cancer patients live only 10 months if they were diagnosed stage 4, even with agrresive chemo plus avastin (bevacizumab). In an article published 3 years ago in jco, it was found that chemo plus chinese herbs resulted in 12 months median survivals, indicating the importance of integrative care. Also, there're case reports of complete cures with "unapproven therapy"(you can find them pubmed). Research!

You are very brave: To face this and to turn away from treatment, and i wish you well. Forecasting survival is not science. Much depends on where your disease moved, how much weight you have lost, how much daily activity can you do. Doctors usually give a "median survival" a point on a curve where 50 % are stll alive, but 50% die before then, and ineed, 50% die after.