Close Relative Mis-diagnoised lung CA. Is it terminal?

Initial symptoms little over 12 months ago were; Anaemia / dizziness treated repeatedly with iron tabs and same time Pain started in right hand (two middle fingers). By Christmas 2013 Pain had crept up arm and into shoulder. Was prescribed paracetamol, then nerve pain tabs. Relative asked GP for scan and was told GPs not allowed to refer. Pain getting worse and tabs having no effect when relative sent fax to GP asking again for scan. GP replied that they were not allowed to refer for scans in the area. They then sent relative to Care Uk who referred problem to 3 different areas (30 mile Radius) in the city for the various tests = nerve conduction, MRI &, CT SCAN while throughout all procedures being told there is no patient choice allowed. Outcome is that relative has cancer on outside of right lung which had spread to spine & neck = (C5 to T3) . Further MRI shows no brain involvement. Was referred for immediate attendance allowance and blur badge parking. Given 5 sessions of emergency Radio therapy while awaiting biopsy's. Since then is on 3rd chemo cycle. Told at last review that latest results show no new spread and chemo is working. What does the chemo do to the tumours and are they getting smaller/ reducing in size till they eventually disappear? Or is this terminal.