In the United States, racial variations have been documented in the incidence, mortality, and clinical management of cancers of the breast, colon, lung, and prostate.[1-4] In conjunction with similar findings from nonmalignant diseases, such as cardiovascular and cerebrovascular disease, these data suggest that racial variations in medical care are widespread.[5-8] However, few empirical studies explain why these racial variations exist at all.
There are several potential explanations for these findings. First is a consideration of racial discrimination in medical care. Second, differences in socioeconomic status and income, rather than race, might be important factors. For example, racial differences in incidence and survival for some cancers have been linked to socioeconomic status.[10-12] Socioeconomic status may also account for variations in patterns of care.
Third, clinical factors may differ according to race/ethnicity, including disease pathophysiology, stage at presentation, or comorbid conditions that may be contraindications to some therapies or otherwise modify the choice of treatment. Fourth, there may be racial or cultural differences in patient preferences for care.
Understanding the extent of, and factors associated with, racial variations in the care of men with prostate cancer is especially important. Recent advances in prostate cancer screening have resulted in higher rates of early-stage disease among whites more so than blacks.
The Concept of Race
Race is regarded as a social concept that reflects historical social and economic events and not as a biological entity.[13-15] Indeed, some health researchers contend that race has no biological meaning and should be abandoned as a variable in analyses, particularly because the concept has been used in the past to bolster racist arguments of the purported inherent superiority of some racial groups.[16,17]
The socioeconomic aspects of race have been evaluated previously, while potential biological aspects have been virtually ignored.[18,19] Although race is intimately intertwined with socioeconomic status (at least in the US), the two terms reflect different concepts.[20,21]
For example, race may also be an indicator of genetic proclivities for cancer development, a proxy for economic factors, eg, ability to pay for care, or a marker for cultural orientation, eg, patient preferences for certain therapies or misunderstandings about some therapies.
The policy implications of these alternative explanations are widely different, varying from educational strategies, health care financing reform, or program targeting to high-risk populations.
Among males, prostate cancer is second only to lung cancer in incidence and mortality, with significant racial differences in both factors. In 1992, the age-adjusted incidence rate for prostate cancer was 187.6 per 100,000 for blacks vs 139.4 per 100,000 for whites, yielding an overall rate ratio of 1.3.
The age-adjusted mortality rate for prostate cancer for 1988 to 1992 was 53.5 per 100,000 for blacks vs 24.0 per 100,000 for whites, a mortality rate ratio of 2.2. This is one of the largest ratios for site-specific cancer mortality.
Blacks consistently present at a later stage of prostate cancer. However, adjusting for stage at presentation does not eliminate the racial disparities in survival rates; rather, the survival gap between blacks and whites demonstrates a broadening with advanced stage.
Patterns of Care
Racial/ethnic differences are apparent in the care of prostate cancer patients. For example, black patients are substantially more likely than whites to receive hormonal therapy alone but are less likely to undergo prostatectomy alone. This pattern appears to persist over time.
There is a relatively extensive and consistent literature regarding the role of clinical and socioeconomic factors in explaining racial differences in types of prostate cancer therapy, but no literature on the importance of either patient preferences or the patient-physician interaction.
It is not known if differences in care contribute to the lower survival rates among blacks. Some studies have reported that when treatments are similar between blacks and whites, outcomes are similar. Among patients on standard oncology protocols, there is uniformity in evaluation and treatment, as well as overall survival and disease-free survival. Similarly, in equal access systems, no significant racial difference in overall survival is reported.[23,24]
However, the literature linking specific treatments with outcomes according to race does not consistently indicate these findings. In one study, time to recurrence was shorter among the black vis-à-vis the white patients who underwent a radical prostatectomy.
Stage at Presentation
Studies suggest that stage at presentation is a primary explanation of the racial difference in therapy. Among patients in the Virginia Cancer Registry who have local or regional disease, blacks are more likely than whites to receive either no treatment or hormonal therapy but less likely to receive either surgery or radiation. With adjustment for socioeconomic, clinical, and health care system characteristics, there is no racial difference in either the likelihood of receiving any treatment versus no treatment or in receiving hormonal therapy or orchiec-tomy versus surgery or radiation.
However, SEER data indicate that, among localized disease patients, blacks are only two thirds as likely to receive radical prostatectomy or radiation.
Ability to Pay
Given the general importance of ability to pay for care in gaining access to health care, it is reasonable to expect that socioeconomic status is an important determinant of therapy. However, review of the evidence from federal and non-federal patterns of care studies suggest that ability to pay may have little or no role in explaining racial variations in the types of therapy for prostate cancer.
Within the health care systems of the Veterans Health Administration or Department of Defense medical centers, financial incentives for providing or withholding care are minimal. However, one patterns of care study found racial variations in care similar to those seen in the nonfederal health care sector.
Moreover, even in studies that control for socioeconomic status, racial differences in type of therapy persist. In addition, clinical factors such as comor-bid conditions may account for some of the variation in care.
Finally, ability to pay is just one dimension of socioeconomic status. Other dimensions of socioeconomic status, such as education or knowledge, may be worth exploring as possible additional factors that have a role in explaining the racial differences in prostate cancer therapy.
Variations in Patient Preferences
Neither racial variations in patient preferences, knowledge, and beliefs nor the role of the patient's race in the patient-physician decision-making process has been thoroughly investigated as a potential explanation of the observed racial differences in patterns of care.
Recent investigations suggest that blacks are less likely to see themselves as being at high risk of prostate cancer and may have a more pessimistic view of the impact of prostate cancer on quality of life and of the prognosis.[28-30] Such attitudes may indirectly account for the racial differences in the therapies used by influencing when in the natural history of this disease black patients present.
Given that racial variation in the clinical stage at presentation primarily explains the observed differences in use of therapies, there are at least two compelling avenues for future investigations of racial differences in the treatment of prostate cancer.
One is racial differences in disease pathophysiology and their implications for screening and early detection programs. Blacks may experience a more aggressive form of prostate cancer. There is a long history of epidemiological studies that document a higher incidence and earlier onset of prostate cancer among blacks.[32-36]
Also, time to recurrence may be shorter in black than in white prostate cancer patients, despite similar treatment and similar clinical stage at presentation.[22,25] Finally, latent prostate cancers are greater in volume among blacks than whites.[37,38]
Even if a more aggressive form of prostate cancer does not afflict blacks, studies show consistently that blacks present at a later clinical stage of disease than whites even in equal access systems such as the Veterans Health Administration and Department of Defense.[23,39,40]
Existing evidence, which is far from sufficient, indicates that blacks do not perceive themselves to be at high risk for prostate cancer, while the epidemiology of prostate cancer clearly indicates that they are at high risk. Moreover, blacks may be delaying evaluation because of fears regarding disease prognosis.[28,30]
Prostate cancer is one of several cancers that affect US racial and ethnic groups differently, with blacks experiencing a higher incidence and mortality rate than whites. Black patients with prostate cancer are less likely to receive definitive therapy. This pattern of care difference appears to be attributable primarily to the later clinical stage of disease at presentation; socioeconomic considerations, which relate to access to care, appear to play a lesser role.
Other patient-related factors, for example, preferences for certain therapies, have not been well studied; consequently, their ability to explain racial variations in treatment is unclear.
Potential areas for future research should focus on the reasons for the detection of the disease at a later clinical stage and, hence, its worse prognosis.