Hi TfG. Welcome to the forum.

What you're suffering from is, I think, quite common for those of us who've had a close brush with cancer. In my case I had early stage prostate cancer back in 2010, and for quite a few years afterward I was jumpy and paranoid when it came to the times for my next blood test.  I had some professional counselling which helped somewhat and reduced the intensity of the fear, but waiting for the results was a trial.  It is only in the last couple of years that I've begun to relax somewhat, but the apprehension is still there at test time.

There is this popular meme that all cancer patients are heroes, boldly battling against their disease. The truth is that heroes are rare around here and most of us are s--t scared like you.  You are definitely not alone.