Oncologists usually respond to the question "will chemo keep this lung cancer from recurring" by saying that "adjuvant therapy" in NSCLC has at least a 50% chance of doing that. If you look at the studies they have done on chemo in your type of situation, the results report a "statistically significant lengthening of survival time". A recent study of the chemo agents uracil-tegafur showed similar results. Would the result be even better if they did a study with chemo and natural methods together? I think so, but there is almost no fudning for that kind of research.
As you say, the chemo will certainly cause problems for the person getting it, not the least of which is damage to their immune system. I think it is a good idea to follow a serious program of cleansing, detoxification, and immune strengthening before, during and after any chemo, if you decide to go that route.