Introduction:

Recent evidence has suggested that pathologic Gleason Grade Group 1 (GG1) prostate cancer (PCa) does not exhibit the phenotypic hallmarks of malignancy. Many have therefore suggested reclassifying GG1 as “non-cancer.” However, the metastatic potential of pathologic GG1 has not been extensively studied in high-risk populations. Thus, we sought to examine the metastatic potential of pathologic GG1 PCa in Black men. 

Methods:

The National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) database was queried to identify Black men with primary PCa between 2006 and 2016 and who underwent radical prostatectomy (RP) as first-line treatment. Patients were pathologically staged in accordance with the American Joint Committee on Cancer’s 7^thedition criteria (2010) and stratified by Gleason score in accordance with the 2005 International Society of Urological Pathology (ISUP) grading system. Only patients with pathologically confirmed GG1 PCa and with pelvic lymph node dissections (PLND) were included. Rates of pathologic extraprostatic extension (pT3a), seminal vesicle invasion (pT3b), regional extension (pT4), lymph node and distant metastases were calculated. Other variables analyzed included prostate-specific antigen (PSA) at diagnosis, age, and year of RP. Patients who received previous androgen deprivation therapy or salvage RP were excluded, as were patients with incomplete grading or staging information. 

Results:

We identified 29,299 Black men who underwent RP from 2006-2016. 6,934 (23.7%) of those men were found to have pathologic GG1. 764 patients were excluded, leaving 6,170 patients with GG1 and who underwent PLND in the final analysis (Table 1). Median age was 57 (IQR 52-62) and median PSA at diagnosis was 5.2 (IQR 4.2-7.2) (Table 2). 298 (4.8%) men were pT3a, 88 (1.4%) pT3b, and 33 (0.5%) pT4, while 14 (0.2%) had pathologic lymph node involvement. Six (0.01%) had distant metastasis at diagnosis. Rates of pT4 were significantly more common in the earlier part of the study period.

Conclusion:

Black men with pathologic GG1 PCa have very low rates of metastasis. Nonetheless, ~7% exhibited features of metastatic potential (Stage >pT3a). Reclassifying GG1 PCa as a non-malignant entity is therefore controversial in high-risk groups. This study is limited by the inability to conduct pathologic and metastatic staging review, especially in cases where under-grading or over-staging are suspected. 

Funding: N/A