Researchers reviewed clinical and demographic data from records of 864 patients diagnosed with prostate cancer at four Chicago-area hospitals between 1986 and 1990 to evaluate the effect of other health care conditions on survival among black and white men. The Robert Wood Johnson Foundation awarded Dr. Freeman a fellowship in the Harold Amos Medical Faculty Development Program. His findings are relevant to RWJF's strategies for addressing racial and ethnic disparities in health care.
Q: What was your study's objective?
A: We wanted to know whether differences in the number of comorbidities or other medical conditions present at the time of a prostate cancer diagnosis help explain some of the large differences in mortality between blacks and whites from the disease.
Q: How do black men suffering from prostate cancer fare in comparison to white men?
A: Following a diagnosis of prostate cancer, black men are more likely to die of the disease or another health problem than are white men with the disease. They tend to be diagnosed at later stages or when the cancer has spread beyond the prostate gland itself, to other organs or sites.
Q: Traditionally what hypotheses exist to explain this disparity?
A: There are a few. The main one is that, as a result of inherited biological differences, prostate cancer is inherently more aggressive among African Americans and therefore more deadly. Some believe the differences in mortality reflect differences between blacks and whites in seeking out screening tests and other types of preventive services. Some have suggested that differences in lifestyle may play a role, that African Americans may be more exposed to factors from the environment or life or dietary factors might influence the degree of aggressiveness of prostate cancer. The hypothesis we were testing was a novel one. Researchers have not looked at the role of comorbidities, or the impact of other health conditions, on survival differences between blacks and whites with prostate cancer.
Q: So you believe that the presence of another health condition factors into a male prostate cancer patient's prognosis?
A: Clearly it does. Prostate cancer tends to be a slow-growing cancer compared to other cancers. Among men with prostate cancer diagnosed at the early stage, several studies have shown that the presence of other health problems at the time of diagnosis is an important determinant of whether the patient will die of the prostate cancer, if it's left untreated, or die of another health problem instead. Estimating a man's likelihood of dying from another medical condition instead of prostate cancer plays an important role in the everyday diagnosing and treating of prostate cancer.
Q: What are common comorbidities prostate cancer patients suffer from?
A: Coronary artery disease, diabetes and stroke. These are the same important causes of death you find in the general population.
Q: What did your study find?
A: We found a little of the opposite of what we set out to find. Absence of a significant medical diagnosis at the time of the prostate cancer diagnosis raised the likelihood of dying from prostate cancer for African American men as compared to white men. However, the more comorbidities you had at the time of your initial diagnosis, the gap disappears. In addition, we also found that patterns of care varied between blacks and whites. African American men were less likely to receive curative therapy, such as surgery or radiation, if their disease was in early stage. We also found that early-stage prostate cancer diagnosis was also associated with a lower risk of death from causes unrelated to prostate cancer.
Q: So what typically do black men with prostate cancer die from?
A: Diabetes among African Americans appears to be more severe and also is complicated by eye, kidney or other problems. When African Americans had a stroke, they tended to have some neurological difficulty that remained afterwards. African Americans also were more likely to have kidney disease or problems at the time of their prostate cancer diagnosis.
Q: What is the effect of co-morbidity on racial differences in survival?
A: In both black and white men, the presence of other medical conditions is an important determinant of whether a patient will die of prostate cancer or of another medical condition. However, when you are looking at racial disparities, we found the absence of a comorbidity was actually associated with a higher risk of death among African Americans relative to white men.
In this setting, we believe that comorbidities are a surrogate, or a proxy, of your relationship with the health care system. The more a provider knows about the patient, the more connected the patient is to the health care system. More connected people may have greater opportunity for disease control or intervention when there are existing problems.
I would like to emphasize the impact of racial variation in the care that men with prostate cancer receive. It's a non-trivial problem. Research shows that if African Americans and other groups do not receive therapy comparable to whites who are in early stage of disease, their risk for mortality increases from any cause. It's not just there are racial differences in patterns of care. The racial differences in patterns of care also translate into racial differences in mortality. Whether that's an effect of less well-controlled prostate cancer or less well-controlled or recognized codes of illness remains to be established.
Q: What are the policy implications related to your findings?
A: We need to focus on a more comprehensive set of health problems in relation to prostate cancer when thinking of ways to reduce the black/white mortality rate. The way to reduce the black/white mortality rate for prostate cancer may not be through screening per se but through a more comprehensive assessment of access to care in general.