© 1999 by Oxford University Press
Journal of the National Cancer Institute, Vol. 91, No. 9, 801-802,
May 5, 1999
© 1999 Oxford University Press
CORRESPONDENCE |
Re: Race, Prostate Cancer Survival, and Membership in a Large Health Maintenance Organization
Affiliation of authors: Department of Radiation Oncology, University of California, San Francisco.
Correspondence to: Mack Roach III, M.D., Department of Radiation Oncology, University of California, San Francisco, 505 Parnassus Ave., L-34, San Francisco, CA 94143-0226.
We believe that the article by Robbins et al. (1) was generated with good intentions; however, this study does a disservice in improving our understanding of the relationship between prostate cancer and race. The authors made numerous assumptions that require commentary.
First, cancer researchers do not decide that hormonal therapy or chemotherapy prolongs survival in prostate cancer, breast cancer, or any other cancer on the basis of large population-based studies (2). The U.S. Food and Drug Administration approval for the use of a new drug is not based on large, crude, population-based studies. If the sample size for these studies is adequate to show small treatment effects as independent prognostic factors, they should be large enough to detect a meaningful independent effect due to race. The use of large numbers of patients does increase the statistical power, but it also increases the risk that if there are differences in the incidence of screening, work-up, quality of care received, support systems, or other socioeconomic factors (not included in the analysis), then the conclusions are likely to be in error. Instead, we conduct carefully designed prospective randomized trials with well-defined stratified risk groups of patients who are systematically and uniformly staged, treated, and followed to eliminate various sources of potential biases. To date, all analyses of data from prospective randomized trials have failed to demonstrate an independent prognostic significance due to race (3-4). The authors did not comment on any of these studies.
The article by Robbins et al. (1) contributed little new information. Studies (3,4) based on crude, population-based data have demonstrated that blacks present with more advanced prostate cancer. The suggestion that their report was unique because it involved a putative "equal access" health maintenance organization is overrated. They assumed that health plan members all utilize health care equally. They provided no data to support this assertion. In fact, numerous studies have demonstrated that blacks are treated differently than whites. For example, with the same severity of heart disease, whites are more likely to receive cardiac catheterization than blacks (5). The point is that equal access does not equate to uniform treatment, and there are known examples of differences in treatment by race (5,6).
It is an error to group patients into broad staging categories called "local" and "regional" and assume that there are no important differences in outcome. The extent of disease and the corresponding prognosis associated with particular cancers are actually continuous and not simply discrete units of prognosis. Numerous studies have demonstrated that clinical stage is a crude measure of the true extent of disease in prostate cancer. A major flaw in this study was to group clinical patients with stage C disease and patients with known lymph node metastasis; such patients have quite different prognoses. No modern randomized trial would stratify only on the basis of stage. Pretreatment prostate-specific antigen and Gleason scores are the major determinants of pathologic stage and ultimately the outcome in patients with clinical, localized prostate cancer.
These authors assume that tumor grade should not be accounted for in the analysis of race. Tumor grade increases with stage and as such, is not likely to be independent to the time of diagnosis. The question should not be, "if a black person presents with a higher stage and grade tumor and they are treated differently, are they more likely to die of it?" The question should be, "if a black person presents with the same grade and stage and gets the same treatment, are they more likely to die of it due to this concept that we call `race'?" Furthermore, the distribution pattern differences noted between blacks and whites with prostate cancer are not unique to prostate cancer. The stage at presentation for blacks is higher for most cancers, including cancers of the breast, lung, and esophagus. For all of these sites, analysis of prospective randomized trials have demonstrated that race has no independent effect.
In this article, the authors conclude that there is an increased virulence of prostate cancer in
black men. However, in an earlier study, Whittemore et al. (7) showed
that there was no difference in the rate of rise of prostate-specific antigen levels by race in a
longitudinal study. This lack of difference suggests that there is likely to be no difference in
virulence over time. An even more convincing argument against the conclusions of these authors
is provided by their own data [see (1), Table 1].
If the difference between the stage and tumor grade among blacks and
whites within the Kaiser system is explained by biologic differences, the same argument could be
made comparing whites within the Kaiser system to non-Kaiser whites (Table 1). Only 53.7% of non-Kaiser whites had localized disease compared with
62.6% for Kaiser whites and 55.2% for Kaiser blacks. Even more impressive is the
fact that the adjusted death rate ratio among Kaiser blacks with localized disease was 69.4 and
that of non-Kaiser whites was 69.0. However, Kaiser whites had a ratio of 63.6 but non-Kaiser
blacks had a ratio of 75.2. Does this mean that non-Kaiser whites are biologically similar and that
Kaiser whites are more biologically different?
|
At the start of this letter, we suggested that the authors had good intentions but that they had done the readers a disservice. The Tuskegee studies were initiated by researchers who believed that there were differences in the natural history of syphilis in blacks and whites. We now know that there are no meaningful differences between blacks and whites diagnosed with this disease. How can these authors confidently conclude that biologic differences can be attributable to race when geneticists can't even define race? Is unemployment, poverty, or lack of education due to race? If by race they mean racism, then we would concur, but if they believe in a biologic construct, we would take issue with this conclusion.
REFERENCES
1
Robbins AS, Whittemore AS, Van Den Eeden SK. Race, prostate
cancer survival, and membership in a large health maintenance organization. J Natl Cancer
Inst 1998;90:986-90.
2
Bolla M, Gonzalez D, Warde P, Dubois JB, Mirimanoff RO,
Storme G, et al. Improved survival in patients with locally advanced prostate cancer treated with
radiotherapy and goserelin. N Engl J Med 1997;337:295-300.
3 Roach M 3d. Is race an independent prognostic factor for survival from prostate cancer? J Natl Med Assoc 1998;90:S713-9.[Medline]cancerlit;99046028
4 Roach M 3d, Krall J, Keller JW, Perez CA, Sause WT, Doggett RL, et al. The prognostic significance of race and survival from prostate cancer based on patients irradiated on Radiation Therapy Oncology Group protocols (1976-1985). Int J Radiat Oncol Biol Phys 1992;24:441-9.[ISI][Medline]cancerlit;93015125
5
Schulman KA, Berlin JA, Harless W, Kerner JF, Sistrunk S,
Gersh BJ, et al. The effect of race and sex on physicians' recommendations for cardiac
catheterization. N Engl J Med 1999;340:618-26.
6
Flaherty JA, Meagher R. Measuring racial bias in inpatient
treatment. Am J Psychiatry 1980;137:679-82.
7
Whittemore AS, Lele C, Friedman GD, Stamey T, Vogelman JH,
Orentreich N. Prostate-specific antigen as predictor of prostate cancer in black men and white
men. J Natl Cancer Inst 1995;87:354-60.
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||