Positive surgical margins after radical prostatectomy vary by PSA, Gleason sum

Seattle-The rate of positive surgical margins after radical prostatectomy in men with either organ-confined or extracapsular disease varies significantly depending on preoperative PSA and pathologic Gleason sum score, say the authors of a study from the University of Washington, Seattle.

The study analyzed relationships among cancer stage, pathologic Gleason sum, and preoperative PSA and positive surgical margin status after prostatectomy in a series of 28,461 men identified from the Surveillance, Epidemiology, and End Results (SEER) database. The operations were performed from 2004 to 2007; 86% of the cohort had pT2 disease and 14% had pT3a prostate cancer.

"Since it is well-established that positive surgical margins after RP portend a greater risk of biochemical recurrence and because positive surgical margin status is one variable influencing patient outcome that is within the urologist's control, it is important for urologists aiming to maximize patient care to understand their own proportion of positive surgical margins in the context of the national average," said first author Marco A. Salazar, MD, PhD, clinical instructor of urology at the University of Washington. "However, existing data on positive surgical margin occurrences are derived mostly from single-institution studies at centers of excellence or from single-surgeon series with low patient numbers.

Margin rate declines over study period

Within the entire study population, 5,538 men (19.5%) had a positive surgical margin. The annual rate of positive surgical margins declined through each year of the study, from 22% in 2004 to 17% in 2007. A significantly higher proportion of men with extracapsular extension compared with those having organ-confined disease had a positive surgical margin (42% vs. 16%, respectively). Analyses of outcomes with men stratified by PSA (<4.0, 4.0 to 9.9, and ≥10.0 ng/mL) and Gleason score (2-6, 3+4, 4+3, and 8-10) showed both of these variables were also associated with a higher number of positive surgical margins, and the relationships were statistically significant.

In analyses conducted with men stratified by tumor stage and then by both PSA and Gleason sum, the proportion of men with positive surgical margins was consistently higher in the pT3a cohort compared with the pT2a cohort for all strata. For both stage subgroups, there were statistically significant associations between positive margin status and both PSA level and Gleason score, but the combination of the two variables had a greater effect on surgical margin status than either variable alone.

For patients with pT2 prostate cancer, a positive surgical margin occurred in 8% of men with a Gleason score ≤6 and PSA <4.0 ng/mL and in 28% of those in the tier with the worst characteristics; ie, Gleason score 8-10 and PSA ≥10.0 ng/mL. Among men with pT3a disease having the lowest risk features (ie, Gleason score ≤6 and PSA <4.0 ng/mL), 28% were found to have a positive surgical margin, but for men with this pathologic stage, the proportion with positive surgical margins reached 63% for those with a Gleason score 8-10 and PSA ≥10.0 ng/mL.

Dr. Salazar observed that SEER captures data for about 26% of the U.S. population. Surgical margin data are not recorded for men with pT3b or pT4 prostate cancer.