July 2016 I got a low-dose CT scan as a long time smoker when I found out it was available through my health insurance at no charge.
I had some issues in July 2017 that sent me to the doctor, who ordered a CT of my right lung, which showed a 2cm x 4cm tumor, tested positive for small cell cancer. I had three doctors all agree it was on the scan done in 2016 but was misread.
If the professionals reading the scans are not paying close attention because they are "pre-screen," early detection will go out the window.