It all depenjds on the staging of the cancer,and how well they respond to treatment. Stage 4 has the worst outcome, but you can keep the cancer controlled and possibly in remission for years.
I had a friend that was diagnozied with lung cancer, heavy smoker and a welder. They gave him 6 months, he died after 6 weeks.
I have an uncle who has stage 4 lung cancer, they gave him 2 years. He's 1.5 years in, but on some miracle pill that appears to be shrinking the tumors, so we're hopeful. He also looks great, works out, walks, watches what he eats. The miracle pill is must better than chemo.
My mom has stage 3c recurent colon cancer, and has been told that she has 8 months without treatment, 2 years with (if it works). But these are just estimates based on her age, tumor staging, agressiveness, etc. Every patient is different and the prognosis can vary. Even if they say 1 year, it could be 2, could be 5, just depends on the patients reaction to treatment, and their desire.
Don't lose hope.