Dr. Koop - Biopsy Underestimates Prostate Cancer in Overweight Men:

Researchers compared the biopsy grade to the cancer grade following radical prostatectomy, which is the removal of the prostate. In 1,113 men who underwent radical prostatectomy between 1996 and 2005 within the Shared Equal Access Regional Cancer Hospital database, 299 men, or 27 percent, had more severe cancer than suggested by biopsy. In 123 patients, or 11 percent, cancer diagnosis was actually less severe.

This was an interesting study that concluded that obesity is one of the risk factors for upgrading at the time of pathological analysis.

The last time I reviewed my database I found that 30% of my gleason 6 cancers were upgraded to 7. I have not done an analysis to see which patients are more at risk yet.