Urgent: 6 cm deep brain cancer with Stage 4 lung cancer, anyone ever had this?

Greetings all!

I really need your comments and suggestions, please.

My father-in-law is near 70 years old. He got diagnosed deep brain cancer with Stage 4 lung cancer. The brain tumor is 6 cm and near the central of the brain. The Stage 4 lung cancer is about 3 cm near the heart.

The brain tumor needs to be treated ASAP. But we are hesitating between knife-surgery and radiotherapy. I would like to hear your experiences. I deeply appreciate your comments and time! Please.

God bless all of you!

Rory