Findings from a retrospective study lend support to the idea that even in men with a Gleason 7 (3+4) biopsy score, prostate cancer may sometimes act like low-risk disease.
Durham, NC-Findings from a retrospective study lend support to the idea that even in men with a Gleason 7 (3+4) biopsy score, prostate cancer may sometimes act like low-risk disease.
The research, presented at the AUA annual meeting in New Orleans, used the Shared Equal Access Regional Cancer Hospital (SEARCH) database to identify men who underwent radical prostatectomy between 2001 and 2013 and had a PSA ≤10.0 ng/mL, stage cT1c/T2a prostate cancer, more than eight cores taken on biopsy, and a biopsy Gleason score ≤7 (3+4 only for a score of 7). In analyses restricted to men with three or fewer positive cores, comparisons between groups with a biopsy Gleason score ≤6 versus a Gleason biopsy score of 7 found no significant differences in the biochemical recurrence rate or in certain adverse pathologic outcomes, reported first author Kathleen McGinley, DO.
“These findings add to a growing body of studies addressing the question of whether certain men with intermediate-risk prostate cancer could be reasonable candidates for active surveillance,” said Dr. McGinley, a Society of Urologic Oncology fellow in the division of urology, Duke University Medical Center, Durham, NC.
“However, we need to be mindful that this is a retrospective review of patients who underwent radical prostatectomy. Therefore, we must be cautious about trying to extrapolate our findings to the natural history of prostate cancer in these men with low-volume, intermediate-risk disease,” added Dr. McGinley, who worked on the study with Stephen J. Freedland, MD, and colleagues.
Using the SEARCH database, Dr. McGinley and colleagues identified 874 men who met their inclusion criteria for PSA, clinical stage, and biopsy features, and had complete follow-up data available. The men were first divided into two cohorts representing those meeting the traditional AUA criteria for low-risk disease based on a biopsy Gleason score ≤6 (497 men) and those with Gleason 7 “low-risk” disease (377 men).
In a model adjusting for age, year of surgery, race, surgical center, clinical stage, and PSA, logistic regression analysis found that men with Gleason 7 low-risk disease were significantly more likely to have pathologic Gleason ≥4+3 disease, extracapsular extension, and seminal vesicle invasion than the AUA low-risk men. In addition, multivariable Cox hazards analysis adjusting for clinical and demographic features showed the biochemical recurrence risk was significantly higher in the Gleason 7 low-risk group, and in a Kaplan-Meier analysis, the separation between groups occurred early during follow-up.
To investigate whether a subset of the men with Gleason 7 low-risk disease had outcomes comparable to those of the AUA low-risk men, the analyses were repeated using increasingly strict definitions of low-volume prostate cancer (ie, percent of positive cores <33%, ≤4, ≤3, and ≤2 positive cores). Only when the cohort was narrowed to men with three or fewer positive cores, which included 67% of the AUA low-risk group and 42% of the Gleason 7 low-risk group, did the significant between-group difference in biochemical recurrence risk disappear. In addition, there were no longer statistically significant differences between the men with Gleason 7 low-risk cancer and the AUA low-risk group in risks of extracapsular extension or seminal vesicle invasion.
Dr. McGinley mentioned that because of the changes that occurred in Gleason grading during the study period and as patient case mix has continued to evolve, analyses were also conducted looking only at men who underwent surgery after 2009. The results in this more contemporary group were the same as in the overall population.
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