@franciekid, yes, that's what we all pay attention to with Tagrisso. I reviewed a research paper where the researcher said, "TKI resistance is inevitable." as part of his pitch for the proposed research. Unfortunately, no one can tell when the cancer will develop resistance.

I have one friend who has been on it for 7 years. Like me, he's had one recurrence that was treated with radiation and no further recurrence since then. In my case, my radiologist speculated that maybe the initial surgery and radiation missed a few cells that took 4 years to grow into something detectable because I was taking Tagrisso all that time. My oncologist ordered another ctDNA after the radiation and is convinced that I experienced a recurrence and not resistance.

I did learn two things about Tagrisso after I'd been taking it:
1. Some people can skip a day or two on a weekend without a problem. My oncologist has decided that I am not one of those people after I had the recurrence. I haven't missed a day since.
2. Beyond that, it's essential for some of us to take it at the same time every day to maintain a constant level in the bloodstream. Once you say it, it seems obvious, but that was not part of my early instructions.

Yes, the thinking/reasoning/humor part of my brain is intact. The cyst was near the left parietal lobe, which influences muscles on the right side of my body and coordination between the two sides. I used to be much more athletic than I am now, which is frustrating, but in the grand scheme of things . . . Here's hoping that none of us on Tagrisso experience resistance any time soon!