system
Given the following post, respond as if you're commenting on Reddit:
human
What exactly makes a tumor inoperable?

I have a friend who has been fighting a glioblastoma.  He was recently told by his doctors that the tumor has doubled in size to 2 inches and is inoperable, and that likely has up to 2 months to live.  

What exactly makes a tumor inoperable?  And in a situation like this, why wouldn't you attempt the long shot at operating?
gpt
Proximity to essential anatomy. 

Tumors can invade and surround essential parts of the body. This particularly true of tumors within delicate areas like the brain. 

This is where the expertise of the oncologist and surgeons comes in. They assess each individual case and weigh the post-operative quality of life, and potential for relapse. Also, glioblastoma's are particularly invasive, and resection might cause further spread.