So my dad was diagnosed with stage IV adenocarcinoma. He has gone through three rounds of Keytruda and things had been going well. His tumor has shrunk significantly, and according to some recent scans so have his lymph nodes. Last week he went in for some lower back pain to find that there had been a lot of fluid on his lungs. After some testing they have determined that the fluid is malignant. Haven't had any answers yet from oncologist about what treatment will continue or not? Have never gone through this, there isn't much on the internet about it, and no feedback from doctors has me very anxious! Any information specific to this would be helpful!