There was a substantial difference in prostate cancer diagnosis across ethnic groups: 25% of Black men with a raised PSA were diagnosed with prostate cancer within 1 year of being tested, compared with 20% of White men and 13% of Asian men, in the analysis of a large primary care cohort in the United Kingdom.
Incidence of advanced prostate cancer for Asian men with a raised PSA result was 4.5%, compared with 7.5% for White men and 7.0% for Black men.
Men included in the study were aged 40 and older and had no prior cancer diagnosis. Their ethnicity and PSA test result were logged in a national dataset between 2010 and 2017.
The study of more than 730,000 men, published in BMC Medicine, didn’t explore reasons for the differences, but experts offer their thoughts on what led to the findings and what these results imply.
Why the Higher Diagnosis Rates but Not More Advanced Disease in Black Men?
Lead author Liz Down, a graduate research assistant at the University of Exeter, Exeter, England, suggests the higher diagnosis rates but not more advanced disease in Black men may be linked to genetic variations.
Her team’s studies have shown that Black men in the United Kingdom and United States have higher levels of PSA. The PSA value is used to identify patients who might benefit from specialist investigation, and current guidelines in the UK and US don’t distinguish between ethnic groups.
As most men have slow-growing prostate cancer, this may lead to a disproportionately higher number of Black men being diagnosed with prostate cancer, she said.
“One possible interpretation,” Ms. Down notes, “is that prostate cancer follows a similar trajectory in Black and White men. What is different, however, is that Black men have higher PSA levels.”
As to why the advanced-cancer incidence is similar in Black and White patients in the study, Daniel George, MD, director of genitourinary oncology at Duke Cancer Institute in Durham, North Carolina, says it’s important to understand that the Black men in this study “are not necessarily representative of the Black population at large.”
In this study, “they’re a little bit more healthcare inclined,” Dr. George notes. The study population is actively seeking the PSA test. Their socioeconomic profile might be closer to their White counterparts’, and that may make results more similar, he said.
“It’s possible that because this is a screening and not just men coming in for symptoms or cause, that we’re not seeing as much advanced disease,” he continued.
Amar Kishan, MD, chief of the genitourinary oncology service at University of California Los Angeles (UCLA) Health, says the genomic factors and environmental stressors that lead to elevated PSA counts don’t necessarily translate into aggressiveness of disease.