[859] Incidence of Reclassification in Patients Undergoing Active Surveillance for Favorable-Risk Prostate Cancer.

Jeri Kim, John W Davis, John Ward, Xuemei Wang, Curtis Pettaway, Louis Pisters, Surena Matin, Deborah Kuban, Steven J Frank, Andrew K Lee, Ina N Prokhorova, Victoria T Brown, Christopher J Logothetis, Patricia Troncoso. The University of Texas MD Anderson Cancer Center, Houston

Background: Morphologic characterization of prostate cancer (PC) in ultrasound-guided biopsies (BXs) has been used to determine risk stratification and need for therapy (Tx). BX schemes have evolved to ensure adequate sampling of the prostate. In a prospective cohort trial of active surveillance (AS), patients (pts) with early-stage PC are stratified into 3 groups: Gr I (low risk), Gr II (AS is pt's choice), and Gr III (competing comorbidities prevent local Tx). To standardize data, we began requiring all pts to have a repeat BX (re-BX) within 6 mo of study entry according to an 11-core BX scheme that is also used during surveillance. We report our experience with an emphasis on BX findings in Gr I.
Design: Eligibility criteria: Gr I pts: Gleason score (GS) 6 (3+3), one positive (pos) core (<3 mm), and a total prostate-specific antigen (PSA) level <4 ng/mL or GS 7 (3+4), one pos core (<2 mm), and PSA level <4 ng/mL. Gr II and Gr III pts must have clinically localized disease. Pts are monitored every 6 mo by PSA, testosterone, and digital rectal exam. At yr 1, all pts must undergo re-BX and thereafter follow a predetermined BX scheme based on pathologic findings. Definitive Tx is offered for unequivocal clinical and/or radiographic progression or when ≥1 of the following is detected at postenrollment Bx: increased tumor length in pos core, ≥2 pos cores, or upgrading of tumor. An increase of >30% in surveillance PSA from baseline level is also considered reclassification.
Results: From February 2006–May 2010, 378 pts enrolled; 376 met eligibility criteria (92 before June 2007 re-Bx requirement). Of 136 Gr I pts, 42 were enrolled before and 94 after the re-BX requirement. During surveillance, 17 (12.5%) pts met the reclassification criteria on re-BX, 10/42 (24%) before and 7/94 (7.4%) after re-BX requirement (before: 1 yr, 6; 1.5 yr, 1; 2 yr, 3; after: 1 yr, 6; 2 yr, 1). Of the 17 reclassified pts, 4 chose Tx. No pt met PSA reclassification criterion in Gr I. Of 228 Gr II pts, 45 were enrolled before and 183 after the re-BX requirement. Included in the 183 were 45 (24.6%) pts who were restratified to Gr II because of a re-BX; 14 of these pts chose to have Tx.
Conclusions: For appropriate risk stratification, repeat extended BX should be considered for men choosing AS. Prostate BXs in favorable-risk PC have a high sampling bias rate and should be accounted for in AS protocols. Reclassification owing to sampling bias on re-BX vs true disease progression needs further investigation.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 1:00 PM

Platform Session: Section A, Monday Afternoon

 

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