I am sure that your Father wants to protect you from worry and fear. He probably does not want to be confronted on this, and he has a choice to make of what treatment is best for him.
My husband was diagnosed with Lung Cancer in May of 1998 and he opted for surgery and herbs. He also later on needed Chemo and Radiation for new outbreaks. He went thru some bad times with both treatments.
The only pills he actually took were morphine for the pain. The Cancer can be painful and pain control is very important.
If you want more information call his doctor and try to let him know your concerns and how to deal with this. Study up on Lung Cancer and I hope all works out well for the both of you.