Success in stage 4 lung cancer can occur when doctors are able to personalize the treatment plan. They take into account the patient's overall health, the type of lung cancer (such as non - small cell or small cell), and any genetic factors. If a patient has a particular genetic mutation, there might be a drug designed specifically for that mutation. In addition, lifestyle changes like quitting smoking and reducing stress can also contribute to better outcomes. For instance, a patient who quits smoking during treatment may respond better to the medications as the body is no longer being exposed to harmful tobacco chemicals, which could have been interfering with the treatment.