I posted "my ad lung cancer mets to his brain" last week.
Fluid also developed in his lung,
He can choose to 1) drained off the fluid when it is getting more (everytime) but each time he do it, there is a risk that he will develop infection in the area where the needle is put in.
2) To permanent (though according to the doctor, about 15% chance the fluid may come back again) stop the fluid from building up again, drained off the entire fluid and apply a talc (layman term = glue) to irritate the pleura and make them stick together, thus there will be no more space for the fluid to collect.
If unforunately, after option (2), fluid buid up again, then the process will have to repeat again.
So far he is okay. Next scan will be late this mth.
Hope your mum-in-law speedy recover.