Hi- sorry to hear about your mom's pc. Both places can have serious affects, but the lungs are so essential to life. You may be dealing with breathing difficulty or pneumonia or other infections. Oxygen might become necessary.
There's a lot of helpful info you can find on the web. Try a search with pc and lung cancer. Pancan.com is a great resourch, as well as pages here on cancercompass.
I hope you can spend time with your mom. Help her focus on things that make her happy. Pray with her or find someone who does that for cancer patients. Help her find peace. We never know how much more time we have. My dad goes for another ultrasound on Wednesday. I'm hoping his cancer hasn't spread. He is so weak at times.
Will pray for you for comfort and strength in this tough time. rt