From the 6/1/10 AUA Daily Scope:

Quoted from the International Journal of Radiation Oncology, 60-70% of men with low stage, low grade prostate cancers, with PSA less than 10 (frequently managed with Active Surveillance), will be found at Radical Prostatectomy to instead have bilateral and higher grade disease. This implies a risk for local or distant recurrences due untreated active disease.

And, from Prostate Cancer and Prostate Diseases: Men with Gleason 3+3 cancer and PSA’s in 2-3.9 range have 32.6% chance of having Gleason 7 or higher at Radical Prostatectomy when the whole gland can be examined. If the PSA is 4-10 in these men, 44% have higher grade cancer when the gland is examined after Radical Prostatectomy.

There’s more: From Northwestern University, investigators found that men with low risk prostate cancer who waited more than 6 months for surgery had double the risk of being found to have high grade cancer, and double the risk of biochemical (PSA) recurrence than those treated before 6 months after diagnosis. They conclude men with low grade cancer should be counseled on the increased risks of worse outcomes if they wait longer than 6 months for treatment.

May make us think twice on the safety of the Active Surveillance approach.