|
Advertisement |
|
|
||
 |
|
|||||
|
|||||
|
 |
||||||
|
||||||
|
||||||
|
Journal of Clinical Oncology, Vol 22, No 20 (October 15), 2004: pp. 4193-4201 © 2004 American Society of Clinical Oncology. DOI: 10.1200/JCO.2004.09.127 Racial/Ethnic Differences in Functional Outcomes in the 5 Years After Diagnosis of Localized Prostate CancerFrom the Departments of Preventive Medicine and Urology, University of Southern California Keck School of Medicine, Los Angeles, CA; Medicine Service, New Mexico Veterans Administration Health Care System; Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM; Program in Epidemiology, Fred Hutchinson Cancer Research Center, Seattle, WA; and Department of Surgery (Urology), University of Connecticut Health Center, Farmington, CT Address reprint requests to Ann S. Hamilton, PhD, University of Southern California Keck School of Medicine, Dept of Preventive Medicine, 1441 Eastlake Ave, Rm 3427A, MC9175, Los Angeles, CA 90089-9175; e-mail: ahamilt{at}usc.edu
PURPOSE: We investigated racial/ethnic differences in functional outcomes up to 5 years after diagnosis among men with aggressively treated localized prostate cancer. PATIENTS AND METHODS: Patients were from the Prostate Cancer Outcomes Study, a population-based cohort study that surveyed patients at 6, 12, 24, and 60 months after diagnosis. Analyses were stratified by primary treatment. Racial/ethnic differences at each time point were assessed using Generalized Estimating Equations, adjusting for pretreatment function, age at diagnosis, secondary treatment, and other confounders. An adjusted summary score for each functional domain was calculated for each time period. RESULTS: Patients included 1,475 non-Hispanic white, 321 African-American, and 279 Hispanic prostate cancer patients. After 60 months, among prostatectomy patients, African-Americans had significantly higher sexual function scores than non-Hispanic whites (43.9 v 36.1; P = .02), but were more likely to have a moderate to big problem with sexual function (50.6% v 44.4%; P = .04). African-Americans also had higher urinary function scores at 5 years than non-Hispanic whites (78.5 v 72.4; P = .04) and were less likely to have problems with incontinence. Changes in sexual and bowel function after radiotherapy showed no significant racial/ethnic differences. CONCLUSION: This long-term cohort study found that, among prostatectomy patients, African-Americans had better recovery of sexual and urinary function at 60 months after diagnosis that was likely to be of mild clinical significance, despite reporting more problems with sexual function than non-Hispanic whites. More study is necessary to understand reasons for these differences. In contrast, no racial/ethnic differences in recovery from radiotherapy were found.
Prostate cancer is an important cause of cancer-related morbidity and mortality. An estimated 220,900 new cases are expected to be diagnosed in the United States in 2003.1 Treatment decision making for the large number of men with newly diagnosed prostate cancer is difficult because the risk of cancer progression must be weighed against treatment-related morbidity and reduction in quality of life.2 Unfortunately, the tools to predict progression for early-stage, localized disease have low predictive values, resulting in many men opting for curative treatment and accepting the risks for long-term reductions in health-related quality of life.3 Furthermore, there is no clear evidence that one treatment is superior to another in terms of survival. To assist in making these decisions, it is necessary to know the long-term consequences of each of the therapy options and the influence of sociodemographic factors such as race/ethnicity. Earlier studies have reported adverse effects of radical prostatectomy and radiotherapy on sexual, bowel, and urinary function.4-14 However, most of these studies were small, cross-sectional, and conducted in referral centers or academic institutions. Furthermore, racial/ethnic variations in outcomes have received limited attention, making it difficult to provide specific information for decision making about treatment.15 In contrast, the Prostate Cancer Outcomes Study (PCOS), on which this study is based, provides information on the complications of radical prostatectomy and radiotherapy for prostate cancer among a population-based cohort of non-Hispanic white, African-American, and Hispanic patients.16 Specifically, we have used data from the PCOS to investigate racial/ethnic-specific changes in urinary, bowel, and sexual function as well as bother from complications over the first 5 years after diagnosis. Based on previous reports indicating that African-Americans may experience poorer outcomes,17 we hypothesized that their recovery of functional status may also be less than other racial/ethnic groups. This report extends previous descriptions of functional outcomes over the first 2-year period after diagnosis among the PCOS subjects.18-20
Methods for the PCOS have been previously described.16 Briefly, the study subjects were randomly selected from men who were diagnosed with primary prostate cancer between October 1, 1994, and October 31, 1995 and who resided in areas covered by six population-based Surveillance, Epidemiology, and End Results (SEER) cancer registries. The areas of residence included the Atlanta, Georgia, metropolitan area; Los Angeles County, Caliornia; King County, Washington (which includes Seattle); and the states of Connecticut, New Mexico, and Utah. Eligible cases included non-Hispanic white, African-American, and Hispanic men who were between ages of 60 to 89 years in King County and younger than 90 years at the time of diagnosis in the other registries. The institutional review board of each participating institution approved the study. Participants in the study completed a self-administered mailed questionnaire at approximately 6, 12, 24, and 60 months after diagnosis, and their medical records were reviewed at 12 and 60 months after diagnosis. During the period of study enrollment, 11,137 men identified in these registry areas met the diagnostic, residency, race/ethnicity, and age eligibility criteria. From these eligible men, 5,672 patients were randomly selected according to specified probability levels in age group, race/ethnicity, and study center strata. Letters requesting participation were sent to 4,736 (83.5%) of the selected cases. Reasons for lack of contact included physician refusal (n = 380), inability to locate the patient (n = 413), and illness or mental incompetence of the patient (n = 143). A total of 3,533 men (62.3%) who completed a 6- and/or 12-month survey were included in the follow-up cohort. Reasons for nonresponse included patient refusal (n = 1,087) and other reasons (n = 116), including foreign language other than Spanish. The questionnaires were translated into Spanish, and interviews were conducted in Spanish when necessary. Medical record abstracts at 12 months were completed for 3,486 (98.7%) of the sampled participating cases. For this analysis, PCOS patients with clinically localized disease who underwent radical prostatectomy (n = 1433) or had radiotherapy (n = 642; including external beam, radioactive seed implants [ie, brachytherapy], and external beam with implants) as primary treatment within 6 months of diagnosis were selected.
Data Collection The mean time intervals between the dates of questionnaire response and initial diagnosis for the radical prostatectomy group were 7.1 months, 9.8 months, 24.6 months, and 61.1 months for the 6-, 12-, 24-, and 60-month surveys, respectively. For the radiotherapy group, the mean time intervals were 8.3, 11.7, 24.4, and 61 months. Vital status was determined by each of the six SEER cancer registries. Dates and types of initial treatment, stage of disease, and Gleason scores were obtained from physician office, outpatient clinic, and hospital records.
Statistical Analysis
Domain-Specific Questions and Composite Function Scores For each domain, a composite score ranging from 0 to 100 was calculated at each time period for each respondent based on the average transformed score across the four or five individual questions that pertained to the domain. For this composite summary score, all categories of response to each question contributed to the total score. A man who was not limited in any of the functions included for a specific domain would receive a score of 100 for that domain. For a composite score based on five questions (with four levels each), there would be the potential of scoring 20 points/question if the respondent had the highest function. Decline of one level for any question would result in a loss of five points or a 5% decline. The mean composite function score was analyzed as another outcome measure. Linear regression models using weighted least squares estimates were used to compare adjusted mean function scores between the race/ethnicity groups at each time point.
Effect of Attrition at 5 Years on Race/Ethnicity Comparisons Demographic factors at baseline that were related to response at 60 months or differed by the race/ethnicity for each treatment group were identified, and these factors were included in the models. In addition to these demographic factors (which included age at diagnosis), any additional treatment other than initial treatment and recurrence status of prostate cancer were included in the model at each time point.
Overall, response to the 60-month survey was significantly higher for non-Hispanic white men among the radical prostatectomy patients, where 80.4% of the initial non-Hispanic white participants completed a 60-month survey compared with 68% of African-American and 77% of Hispanic men. Smaller differences in response by race/ethnicity were found for radiotherapy patients (66% of non-Hispanic whites, 61% of African-Americans, and 66% of Hispanics). These differences were not attributable to different rates of death. The baseline and 6-month function scores of 60-month survey respondents and nonrespondents were also compared (data not shown). Among non-Hispanic white men who received radical prostatectomy, the adjusted baseline mean sexual function scores were significantly higher for respondents than nonrespondents regardless of vital status (P = .009 and .04 for nonresponse because of death and other reasons, respectively), and no differences by response were observed for urinary or bowel function. Although nonsignificant, African-American respondents compared with nonrespondents had lower sexual and bowel function scores for men treated with radical prostatectomy and lower function scores in all three domains for men treated with radiotherapy. Among those who initially participated, more men received radical prostatectomy (n = 1,433; 69.1%) than radiotherapy (n = 642; 30.9%), and these percentages were similar among the racial/ethnic groups. African-American men had the youngest age distribution within both treatment groups, especially among the radiotherapy patients (Table 1). Non-Hispanic white men were the most educated and had the highest incomes, whereas Hispanic men were least educated, were less often employed full-time, and earned the lowest incomes. Hispanic men had the highest proportion of tumors with a Gleason score of 8 to 10. Men receiving radiotherapy reported a higher number of conditions, on average, than men receiving radical prostatectomy (1.7 v 1.2; P = < .0001, data not shown) and, within the radical prostatectomy group, African-American men had a higher number of medical conditions, on average, than non-Hispanic white men (1.5 v 1.2; P = .0001).
Radical Prostatectomy Patients The effects of radical prostatectomy on urinary or sexual function among racial/ethnic groups varied at different points in time after diagnosis (Table 2). Although there were no significant prediagnosis differences in urinary function and perceived problems, when the overall distribution of responses for urinary control at 60-months after diagnosis was compared, African-American men had better urinary control compared with non-Hispanic white men (P = .01). When this distribution was dichotomized between total control versus any leakage, almost half of the African-Americans had total control (49.3%) versus less than one third of non-Hispanic whites (30.8%; P = .004, data not shown). African-Americans were less likely to have problems related to their urinary function compared with non-Hispanic whites (P = .02 for both the overall distribution and for the dichotomized difference between no problem v any problem). Hispanic men reported significantly more sexual activity in the prediagnosis period compared with non-Hispanic white men (P = .0008 for overall distribution and P = .0003 for the dichotomous comparison between  once per week v less often), but not during the subsequent time periods. At 12, 24, and 60 months, African-American men were significantly more likely to report having erections firm enough for intercourse compared with non-Hispanic whites (P = .001, .01, and .03 respectively). Overall, Hispanic men were more likely to report sexual function to be a problem at the 6- and 12-month surveys compared with non-Hispanic whites (P = .008 and .03), and African-American men were more likely to report problems than non-Hispanic whites at 60 months (P = .03). When the distribution was dichotomized between those feeling sexual function was a moderate to big problem versus a small or no problem, the difference between African-Americans and non-Hispanic whites was 50.6% versus 44.4% (P = .04).
The adjusted mean function scores for urinary and sexual function decreased from baseline to their lowest point at 6 months (Fig 1) and then increased, indicating partial recovery of function by 12 months. Little additional recovery was seen for urinary function after that time point (except for African-Americans); however, sexual function continued to improve through 24 months before reaching a plateau from that point through the 60-month follow-up. Among African-American men, the adjusted mean urinary and sexual function scores were both statistically significantly higher than scores for non-Hispanic white men at the 60-month survey (78.5 v 72.3, P = .04; 43.9 v 36.1, P = .02; respectively), with an average difference of approximately six to eight points. There was no significant difference between the racial/ethnic groups in bowel function for those men treated with radical prostatectomy (data not shown).
Radiotherapy Patients Of the five questions used to assess bowel function, only bowel urgency showed consistent differences by race/ethnicity, as non-Hispanic white men treated with radiotherapy reported more bowel movement urgency than either African-American or Hispanic men in all time periods from 6 months after diagnosis through 60 months, although the differences were statistically significant only at 6 months (between Hispanics and non-Hispanic whites, P = .008); and at 60 months (between African-American and non-Hispanic whites, P = .046; Table 3). The adjusted mean bowel function scores were not different between the racial/ethnic groups at any time point (Fig 2A). No significant differences in the specific sexual function questions were found among the racial/ethnic groups for those men who received radiotherapy, except that, for the overall distribution, Hispanic men were more likely to report their sexual function to be a problem at 60 months compared with non-Hispanic whites (P = .02). Unlike the results for the radical prostatectomy group, the sexual function scores for the radiotherapy group showed no substantial improvement 6 months after diagnosis, and there were no significant racial/ethnic differences (Fig 2B).
We found significant racial/ethnic differences in recovery from radical prostatectomy but not from radiotherapy at 60 months after diagnosis among this cohort of men diagnosed with localized prostate cancer. Among the prostatectomy group, African-American men showed better recovery of urinary function at 60 months and better recovery of sexual function at 12 and 60 months after diagnosis than non-Hispanic white men. However, despite their higher sexual function score, African-American men were more likely to feel that their sexual function was a moderate to big problem compared with non-Hispanic whites at 60 months. Non-Hispanic white patients had, on average, a 60-month sexual function score that was approximately six points lower than that for African-American men. This difference would be equivalent to a decline of approximately one category in one of the five questions used to assess sexual function and could be expected to produce a mild clinical effect that would be noticeable to patients. It is generally held that a change of one third of a standard deviation (SD) is considered to reflect a mild effect, whereas a change of one half of an SD represents a moderate effect.25 Prior studies using these questions in a large multiethnic population of men with localized cancer found the SD of the disease-specific domains to range between 10 and 15 points.11 Therefore a change of three to five points would be considered to reflect a mild effect, noticeable to patients. Few other studies have evaluated longitudinal racial/ethnic functional changes using standardized measures. The CaPSURE study also found that African-American men had better sexual function over time after diagnosis,15 even though they had worse outcomes and slower recovery for other quality-of-life measures including differences in bodily pain, role function, and disease worry. Other studies suggest that there may be racial/ethnic differences in perceiving and reporting functional problems. Although not directly related to prostate cancer patients, one study found that African-Americans might tolerate poorer functional status before downgrading their quality of life.26 For several outcomes, especially those after radiotherapy, we did not find any racial/ethnic differences. This may be due to low power of our study to detect an effect because of small sample size in these subgroups. Although African-American race/ethnicity has previously been shown to predict a worse outcome,17 recent studies that controlled for clinical variables have shown little independent effect owing to race/ethnicity.27-30 In the current study as well, we included several clinical and demographic variables in the multivariate models that may have reduced the effect of race/ethnicity as an independent outcome predictor. We also considered whether study design and data collection factors could explain our results. Differential loss to follow-up is one potential factor, if, for example African-American men with more serious problems were also more likely to drop out at 60 months compared with non-Hispanic white men. Additionally, respondents who completed the study may not have answered all the questions, thus reducing sample size (and efficiency). We assessed possible bias resulting from these events by carrying out sensitivity analyses to determine whether differential loss to follow-up among the racial/ethnic groups affected the results. In general, non-Hispanic white respondents at 60 months had higher earlier mean function scores (at 6 or 12 months) compared with 5-year nonrespondents, whereas African-American 60-month respondents either were not different from nonrespondents or had lower earlier scores (at 6 or 12 months) than nonrespondents. The effect of these differences would be an overestimation of function scores at 60 months for non-Hispanic whites and an underestimation of scores for African-American men, assuming that the relative level of function of the nonrespondents would have remained constant if they had responded at 60 months. Hence the observed better sexual and urinary function outcomes at 60 months for African-American as compared with non-Hispanic white men do not seem to be related to nonresponse bias. Consideration was given to including a Bonferroni adjustment of the P value for determining significance because multiple comparisons have been made. However, two factors suggest that this adjustment may not be appropriate.31 First, the major hypothesis of the study was predefined, ie, to determine whether race/ethnicity was predictive of the outcome measures studied. Second, the outcome variables within each domain are likely to be correlated, eg, an individual with urinary incontinence is also likely to use pads. Under these circumstances, a complete Bonferroni adjustment of the P value would increase the chances of a type II error (ie, accepting the null hypothesis when it is false) as a result of an overly conservative estimate of type I error (ie, rejecting the null hypothesis when it is true). Using a Bonferroni adjustment for correlated variables and the number of P values that we compared (50), a P value of .007 would be considered significant for variables with 1 or 2 df (and would be .001 if no adjustment for correlated variables was made). With this adjustment, some of our findings would not be judged statistically significant. However, the overall pattern of results that we observed was consistent (eg, African-American men with prostatectomies had consistently higher sexual function than comparable non-Hispanic whites at all time points after 6 months). This is seen as more important to understanding the relationship between race/ethnicity and the outcome measures than the statistical significance of a single variable. In conclusion, we found that for men receiving radical prostatectomy, African-American men reported somewhat better sexual and urinary function recovery by 60 months after diagnosis than non-Hispanic whites, but at the same time had more problems owing to sexual function (but not owing to urinary problems). These results did not appear to be due to selection bias. Although the size of these differences seem large enough to be clinically significant, there may be racial/ethnic differences in perceiving functional limitations among men in the different groups, and this is an area in need of further study. Finally, with our ability to control for multiple confounding factors and assess trends over time, we found little racial/ethnic difference in recovery from prostate cancer among those receiving radiotherapy; however, larger sample sizes may be required to confirm this finding.
The authors indicated no potential conflicts of interest.
We thank the men who, by their participation in the PCOS, have contributed to a better understanding of the effects of prostate cancer on men’s lives.
This study was supported by the following contracts from the National Cancer Institute, National Institutes of Health, Bethesda, MD, to each of the participating institutions: grant Nos. NO1-PC-67007, NO1-PC67009, NO1-PC-67010, NO1-PC-67006, NO1-PC-67005, NO1-PC-67005, and NO1-PC-67000. Authors’ disclosures of potential conflicts of interest are found at the end of this article.
1. Jemal A, Thomas A, Murray T, et al: Cancer statistics, 2002. CA Cancer J Clin 52: 23-47, 2002
2. Etzioni R, Penson DF, Legler JM, et al: Overdiagnosis due to prostate-specific antigen screening: Lessons from U.S. prostate cancer incidence trends. J Natl Cancer Inst 94: 981-990, 2002
3. Partin AW, Kattan MW, Subong EN, et al: Combination of prostate-specific antigen, clinical stage, and Gleason score to predict pathological stage of localized prostate cancer: A multi-institutional update. JAMA 277: 1445-1451, 1997 4. Yarbro CH, Ferrans CE: Quality of life of patients with prostate cancer treated with surgery or radiation therapy. Oncol Nurs Forum 25: 685-693, 1998[Medline] 5. Lim AJ, Brandon AH, Fiedler J, et al: Quality of life: Radical prostatectomy versus radiation therapy for prostate cancer. J Urol 154: 1420-1425, 1995[CrossRef][Medline] 6. Fowler FJ Jr, Barry MJ, Lu-Yao G, et al: Outcomes of external-beam radiation therapy for prostate cancer: A study of Medicare beneficiaries in three surveillance, epidemiology, and end results areas. J Clin Oncol 14: 2258-2265, 1996[Abstract]
7. Beard CJ, Propert KJ, Rieker PP, et al: Complications after treatment with external-beam irradiation in early-stage prostate cancer patients: A prospective multiinstitutional outcomes study. J Clin Oncol 15: 223-229, 1997 8. Dale W, Campbell T, Ignacio L, et al: Self-assessed health-related quality of life in men being treated for prostate cancer with radiotherapy: Instrument validation and its relation to patient-assessed bother of symptoms. Urology 53: 359-366, 1999[CrossRef][Medline] 9. Lubeck DP, Litwin MS, Henning JM, et al: Changes in health-related quality of life in the first year after treatment for prostate cancer: Results from CaPSURE. Urology 53: 180-186, 1999[CrossRef][Medline] 10. Shrader-Bogen CL, Kjellberg JL, McPherson CP, et al: Quality of life and treatment outcomes: Prostate carcinoma patients’ perspectives after prostatectomy or radiation therapy. Cancer 79: 1977-1986, 1997[CrossRef][Medline]
11. Litwin MS, Hays RD, Fink A, et al: Quality-of-life outcomes in men treated for localized prostate cancer. JAMA 273: 129-135, 1995 12. Lilleby W, Fossa SD, Waehre HR, et al: Long-term morbidity and quality of life in patients with localized prostate cancer undergoing definitive radiotherapy or radical prostatectomy. Int J Radiat Oncol Biol Phys 43: 735-743, 1999[CrossRef][Medline] 13. McCammon KA, Kolm P, Main B, et al: Comparative quality-of-life analysis after radical prostatectomy or external beam radiation for localized prostate cancer. Urology 54: 509-516, 1999[CrossRef][Medline]
14. Steineck G, Helgesen F, Adolfsson J, et al: Quality of life after radical prostatectomy or watchful waiting. N Engl J Med 347: 790-796, 2002 15. Lubeck DP, Kim H, Grossfeld G, et al: Health related quality of life differences between black and white men with prostate cancer: Data from the cancer of the prostate strategic urologic research endeavor. J Urol 166: 2281-2285, 2001[CrossRef][Medline]
16. Potosky AL, Harlan LC, Stanford JL, et al: Prostate cancer practice patterns and quality of life: The Prostate Cancer Outcomes Study. J Natl Cancer Inst 91: 1719-1724, 1999 17. Grossfeld GD, Latini DM, Downs T, et al: Is ethnicity an independent predictor of prostate cancer recurrence after radical prostatectomy? J Urol 168: 2510-2515, 2002[CrossRef][Medline]
18. Stanford J, Feng Z, Hamilton A, et al: Urinary and sexual function after radical prostatectomy for clinically localized prostate cancer: The Prostate Cancer Outcomes Study. JAMA 283: 354-360, 2000
19. Hamilton AS, Stanford JL, Gilliland FD, et al: Health outcomes after external-beam radiation therapy for clinically localized prostate cancer: Results from the Prostate Cancer Outcomes Study. J Clin Oncol 19: 2517-2526, 2001
20. Potosky A, Legler J, Albertsen P, et al: Health outcomes after radical prostatectomy or radiotherapy for clinically localized prostate cancer: Results from the Prostate Cancer Outcomes Study. J Natl Cancer Inst 92: 1582-1592, 2000
21. Talcott JA, Rieker P, Clark JA, et al: Patient-reported symptoms after primary therapy for early prostate cancer: Results of a prospective cohort study. J Clin Oncol 16: 275-283, 1998 22. Fowler FJ Jr, Barry MJ, Lu-Yao G, et al: Patient-reported complications and follow-up treatment after radical prostatectomy: The National Medicare Experience—1988-1990. Urology 42: 622-629, 1993[CrossRef][Medline] 23. Litwin MS, Hays RD, Fink A, et al: The UCLA Prostate Cancer Index: Development, reliability, and validity of a health-related quality of life measure. Med Care 36: 1002-1012, 1998[CrossRef][Medline] 24. Legler J, Potosky A, Gilliland F, et al: The Prostate Cancer Outcomes Study (PCOS) methods: Validation study of retrospective recall of disease-targeted function. Med Care 38: 847-857, 2000[CrossRef][Medline] 25. Cohen J: Statistical Power Analysis for the Behavioral Sciences. New York, NY, Academic Press, 1977 26. Cykert S, Joines JD, Kissling G, et al: Racial differences in patients’ perceptions of debilitated health states. J Gen Intern Med 14: 217-222, 1999[CrossRef][Medline]
27. Cross CK, Shultz D, Malkowicz SB, et al: Impact of race on prostate-specific antigen outcome after radical prostatectomy for clinically localized adenocarcinoma of the prostate. J Clin Oncol 20: 2863-2868, 2002
28. Johnstone PA, Kane CJ, Sun L, et al: Effect of race on biochemical disease-free outcome in patients with prostate cancer treated with definitive radiation therapy in an equal-access health care system: Radiation oncology report of the Department of Defense Center for Prostate Disease Research. Radiology 225: 420-426, 2002 29. Roach M 3rd, Lu J, Pilepich MV, et al: Race and survival of men treated for prostate cancer on radiation therapy oncology group phase III randomized trials. J Urol 169: 245-250, 2003[CrossRef][Medline] 30. Bianco FJ Jr, Wood DP Jr., Grignon DJ, et al: Prostate cancer stage shift has eliminated the gap in disease-free survival in black and white American men after radical prostatectomy. J Urol 168: 479-482, 2002[CrossRef][Medline] 31. Rothman K: No adjustments are needed for multiple comparisons. Epidemiology 1: 43-46, 1990[Medline] Submitted September 23, 2003; accepted August 3, 2004.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||
|
|||||||||||
|
|
Copyright © 2004 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
|
TOP
ABSTRACT
INTRODUCTION
= 0.05). 
, test of significance on race is adjusted for study center, age, education, income, employment status, comorbidity index, additional radiation, and hormone treatments; 
, test of significance on race is adjusted for study center, age, education, income, employment status, comorbidity index, additional radiation, hormone treatments, recurrence of prostate cancer, and baseline value.
