My father wants to quit chemo after his 1st dose. he has metastatic lung cancer. he is taking herbal meds which has given him relief. how risky to qui?

Death: Of course your father has a right to choose to end his chemotherapy. But, that means his cancer will cause his death.

It is up to him: I would suggest him to discuss with his oncologist. Yes, chemo can give side effects most commonly fatigue etc- but it will be able to increase survival and able to relief the symptoms like pain etc. On average survival for stage IV lung cancer is 15 months- on chemo. Without chemo- it will be only several weeks, few months. Please discuss with his oncologist- re treatment options.