It's not possible to provide a probability of prostate cancer, as each patient will be unique. But a follow-on biopsy is really the way to either eliminate or confirm it.

I had an ultrasound guided biopsy over a year and a half ago (age 67) at my urologist's office with a rising PSA. At that time there was no cancer found from 12 cores. When my PSA continued to slowly rise (trend line up), my urologist recommended an MRI (age 68). From the imaging results there were suspect areas seen and the recommendation was an MRI guided biopsy under a general. Funny thing, the MRI suspect areas gave no cancerous cores from the biopsy, but they did find a few cores in other areas they took samples from. My urologist said they had to look hard to find it, which tells me an MRI is not a definitive for diagnosis, but only one tool for pointing to suspicious areas which may or may not be cancerous. And it's possible it could miss it all together. In my case they are calling it confined to the prostate and I decided on surgery after a second opinion at Mayo in Rochester.

Best of luck with your biopsy! I also recommend a transperineal versus transrectal procedure if you have a urologist that can do it. Risk of infection with transrectal is high and I needed a quick trip back to the hospital the next day and an extended stay to recover.