Hello etb2,
Medical acronyms can be confusing for sure. eGFR stands for “estimated glomerural filtration rate” and is a blood test result that can help determine how well your kidneys are working (or not working). For lung cancer EGFR refers to a genetic marker on lung cancer cells that helps define that particular type of cancer (different genetic mutations can lead to different types of lung cancer). Once the physicians have determined what type of cancer cell mutation you may have then they can prescribed the most effective drug treatments for that specific cancer.
In my particular case I had surgery to remove the right lower lobe of my lung which contained the tumor. The genetic testing of that tumor showed that it had the EGFR mutation which put me on the front line chemo treatment of cisplatin and pemextred (by IV infusion) followed now by daily oral doses of Tagrisso.
I hope this helps!