1. Need to look at the chest CT more carefully to make sure there is no invasion to right chest wall/thoracic outlet (Pancost tumor due to lung cancer). If thoracic outlet invasion is the reason for her arm symptom, then radiation and/or plus chemotherapy may be only the symptomatic treatment option.
2. She need brain CT/MRI with contrast to exclude metastasis as the central causes of the symptom. PET scan may also needed for stagging, or a simple bone scan.
3. Therapy can be iniatiated after stagging and possible tissue diagnosis if considering chemotherapy.
We'll check back again. Best of luck!!!