Hi , so sorry to hear about your mum . It is best to speak to her oncologist  to find out next steps and what treatment plan they will put together .  Is he due to see the oncologist soon ? 

The process I went through was . Ct scan , pet scan . Surgery , biopsy . Chemo .  I didn’t get my staging until the biopsy . When they did the biopsy , they checked for mutation . So I’ve got Braf which means I can have targeted therapy if I need it . 
Your mum should have been allocated a lung nurse , you should be able to call them and ask questions .