--even if it is in remission or cured, you should look into paraneoplastic syndromes that cause neural symptoms, among them neuropathy.

The testing for this is very specialized; not many places do it routinely. Still, its worth checking, as lung cancer is the most common cancer to produce autoimmune based neurological symptoms, and these often persist even after the cancer is dealt with:

http://neuromuscular.wustl.edu/nother/paraneo.htm

http://neuromuscular.wustl.edu/antibody/sneuron.html#hu