Explaining the difference in prostate cancer mortality rates between white and black men in the United States.

OBJECTIVES: Black men have a twofold increased risk of dying of prostate cancer compared to white men. We assessed the extent to which differences in stage and grade at diagnosis, age, multiple primary cancers, and the first course of cancer-directed therapy influence the likelihood of prostate cancer death among diagnosed cases.
METHODS: Incidence-based mortality (IBM) is a method that involves tracking disease cases from diagnosis to death, such that the mortality event is linked to factors identified with the disease at the time of diagnosis (eg, tumor stage and grade). We applied the IBM method to prostate cancer data from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute.
RESULTS: Of men diagnosed with prostate cancer, blacks have a significantly greater chance of dying from the disease than do whites. However, once adjustment has been made for stage and grade at diagnosis, age, number of primary cancers, and initial treatment, no difference in the likelihood of prostate cancer mortality between the two races was found. Differences in stage and grade at diagnosis, age, number of primary cancers, and initial treatment each contributed significantly to the greater chance of dying of prostate cancer for black men than for white men.
CONCLUSIONS: The results of IBM analysis suggest that black men do not have a statistically greater chance of prostate cancer mortality than white men after adjusting for differences in stage and grade, age, number of primary cancers, and treatment. Later stage at diagnosis is the primary reason for the higher likelihood of prostate cancer mortality among black men compared to white men.