The current method of prostate cancer scoring may underestimate mortality risk in black men, according to the authors of a new observational study using the Surveillance, Epidemiology, and End Results (SEER) Prostate Active Surveillance/Watchful Waiting (AS/WW) database.

Among men diagnosed with disease of Gleason grade 6, which is considered to be low-risk disease, blacks had roughly twice the risk of dying from the disease as nonblacks. However, the absolute numbers and percentages were small. Prostate cancer deaths with Gleason 6 disease occurred in 51 of 12,707 (0.40%) black patients vs 155 of 70,938 (0.22%) nonblack patients.

For disease with Gleason scores of 7 to 10, prostate cancer deaths occurred in 275 of 19,134 (1.44%) black patients vs 1206 of 89,445 (1.35%) nonblack patients. Notably, the difference in overall risk for prostate cancer death was not statistically significant between black and nonblack patients after a median follow-up of 3 years. However, among men with Gleason 6 disease, the disparities were statistically significant.

Also, in a subgroup with longer median follow-up, racial disparities between black patients vs nonblack patients were greatest in Gleason 6 disease. The study was published online December 18 in JAMA. The Gleason score is currently the best independent predictor of prostate cancer outcomes. Low Gleason scores suggest that the patient may not need active treatment.

Thus, the principle distinction between Gleason 6 disease and Gleason 7 to 10 disease is that Gleason 6 disease is still considered low risk, and active surveillance may be offered. However, some men with Gleason 6 cancers opt for treatment rather than surveillance, said lead author Brandon Mahal, MD, of the Department of Radiation Oncology at the Dana-Farber Cancer Institute, Boston, Massachusetts.

Disparities in Gleason 6

In their study, Mahal and colleagues investigated prostate cancer–specific mortality by Gleason score and race. They used the SEER Prostate AS/WW database to identify men who were diagnosed with localized prostate cancer from 2010 through 2015. Information on prostate cancer–specific mortality (as of December 31, 2015) was obtained using active and passive surveillance of national and statewide databases.

The authors also conducted an analysis using data from the general SEER database for patients who underwent longer follow-up and were diagnosed from 2004 through 2015. The cohort included 192,224 men, of whom 31,841 were black and 160,383 were nonblack (white, other, or unknown). Compared with nonblack patients, black men tended to be younger (median age, 62 vs 65 years), have clinical T1- to T2a-stage disease (81.3% vs 75.3%), and Gleason 7 to 10 disease (60.1% vs 55.8%) (P < .001 for all comparisons).