Eliminating the disparity in prostate cancer survival between African American and white men may require more than ensuring both populations get equal care.
Not only have mortality rates dropped by about half, but the gap in mortality has narrowed since the adoption of widespread prostate-specific antigen (PSA) screening. Yet African Americans still have a 60% higher incidence of prostate cancer and are about 2 times more likely to die from the disease.
How much racial disparities have really changed, however, remains a mystery, according to a new study by Ruth Etzioni, PhD, of the biostatistics program at the Fred Hutchinson Cancer Research Center, in Seattle, Washington, and colleagues.1
“Reductions in disease-specific mortality have been accompanied by a narrowing of racial disparities in disease-specific survival, leading to some optimism about the ability of screening to reduce established inequities in the burden of the disease,” the authors wrote. “We observe that a sizeable portion of these trends in survival, in fact, are not real; rather, they are attributable to artifacts of screening, particularly in older men.”
Some of the apparent narrowing of racial disparities in survival is, according to the authors, caused by improper accounting for the impacts of lead time — the amount of time between diagnosis and death — and by overdiagnosis. These findings raise questions about the guidelines for PSA screening and whether they should apply equally across ethnic groups.
But the question of equal care, Dr Etzioni said in an interview with Cancer Therapy Advisor, extends far beyond PSA testing — to prostate cancer care in general.
“If we want to equalize mortality we may have to do more for blacks than for whites,” she said. “And the question is why.”
One reason has to do with genetics. Changes in DNA associated with chromosome 8q24 indicate a higher or lower risk for prostate cancer. A study of 2973 single nucleotide polymorphisms (SNPs) in 5 distinct populations identified 7 risk variants.2
“Nearly all of the variants associated with an increased risk of developing prostate cancer were found most often in African American/Black men,” the National Cancer Institute explains on its website, “and certain combinations of these variants were associated with a five-fold increased risk of prostate cancer in men of this racial/ethnic group.”3