You a-priori do not know if you have cancer. The case 1 branches are:

Case 1 without cancer: you're a guy that knows more than doctors because you're the "I have 3 scans on hand guy", so as soon as you open the scans and the doctor says there's a mass, you will say 'OK what can we do???' And then you had a worthless biopsy.

Case 1 with cancer: you saved the 1 week it would take to schedule the new scan and get results and you're basically in the same situation except one week earlier.