Racial Disparities and
Socioeconomic Status in
Association with Survival in Older
Men with Local/Regional Stage
Prostate Cancer
Xianglin L. Du, M.D., Ph.D.
Associate Professor
University of Texas School of Public Health at Houston
Division of Epidemiology
and Center for Health Services Research
Thanks to
Coauthors and Collaborators
Xianglin L. Du, M.D., Ph.D.*
Shenying Fang, MD, MS,
Ann L. Coker, PhD,
Maureen Sanderson, PhD,
Corrine Aragaki, PhD,
Janice N. Cormier, MD, MPH,
Yan Xing, MD, MS,
Beverly J. Gor, EdD, RD,
Wenyaw Chan, PhD
Brief Background
• Racial/Ethnic Disparities in mortality and
survival present in the U.S.
• Higher mortality for prostate cancer in
African Americans compared to Caucasians
are attributed to:
–
–
–
–
–
–
–
More aggressive tumors
More advanced stage at diagnosis
Health insurance and access to care
Difference in screening-early detection
Differences in receiving optimal treatments
Socioeconomic status
Healthcare Providers (physicians and hospitals)
Evidence of Racial/Ethnic
Disparities in Healthcare
Consistent Findings
• Disparities consistently found across a wide range
of disease areas and clinical services
• Disparities are found even when clinical factors,
such as stage of disease presentation, comorbidities, age, and severity of disease are taken
into account
• Disparities are found across a range of clinical
settings, including public and private hospitals,
teaching and non-teaching hospitals, etc.
• Since disparities in health care are associated with
poor outcomes – they are not acceptable
Evidence of Racial/Ethnic
Disparities in Mortality/Survival
not Consistent Findings
• Numerous studies showed that the outcomes
(survival) were similar among different racial/ethnic
groups, after controlling for differences in treatment
and socio-demographic factors
• Whereas
• Other studies showed racial/ethnic disparities still
existed even after controlling for socioeconomic
factors and for access to equitable care and
treatment
• These inconsistency is also apparent in prostate
cancer mortality by race/ethnicity
Objective and Hypothesis
• Main objective is to determine whether there
is racial/ethnic disparity in long-term survival
in a large nationwide, population-based
cohort of older men who were diagnosed
with locoregional stage prostate cancer and
who had universal fee-for-services Medicare
insurance coverage (both part A and B).
• We hypothesized that there were no
racial/ethnic difference in long-term survival
of prostate cancer patents after controlling
for differences in patient characteristics
(age), tumor characteristics (grade-Gleason
score), comorbidity, treatment, and
socioeconomic status.
Study Population and Methods
• Retrospective cohort study of 61,228
men diagnosed with incident (new)
local/regional stage prostate cancer at
age ≥65 (1992-1999 and 11 regions)
• Identified from the NCI’s 11 SEERMedicare data (covering >14% of the U.S.
population).
• Last follow-up: 12/31/2002 with up to 11
years of FU
• >98% completeness of case
ascertainment (incident cases)
Study Variables
• Outcomes
– All-cause mortality
– Prostate cancer-specific mortality
– Time to event (in months from date of diagnosis to date of
death)
• Exposures
– Race/ethnicity: African American, Caucasian, and Hispanics
• Other covariates
– Demographics (age)
– Comorbidity index adjustment (created from Medicare
claims)
– Locoregional stage, but control for grade and AJCC stage
for residual confounding
– Treatment (discuss below)
– Year of diagnosis (1992 to 1999)
– Geographic areas (11 areas)
– Socioeconomic factors (discuss below)
Socioeconomic Factors
(from 1990 census)
• Education - percent of adults aged ≥25 who had
less than 12 years of education at the zip code
level, which was categorized into quartiles.
Poverty - percent of persons living below the
poverty line at the census tract level
• Income - median annual household income at the
zip code level
• Composite SES (socioeconomic status) – that
summed the normal scores of the above three
variables that were equally weighted and
categorized the total scores into quartiles
Treatment
• Primary Treatment:
– radical prostatectomy, or
– radiation therapy, or
– watchful waiting (observational
management)
– all standard of care (for local stage tumor).
• Adjuvant therapy:
– hormonal therapy and
– chemotherapy
– efficacy not confirmed in RCTs.
Figure 1. Kaplan-Meier survival curve by 3 ethnic groups
1.0
Probability
0.8
0.6
0.4
Hispanic
White
Black
0.2
0.0
0
2
4
6
Time (years)
8
10
12
Table 1. Comparison of age
among 3 racial/ethnic groups
Age (years)
Caucasians
n
Median age
(range)
%
73 (65-103)
African
Americans
n
%
72 (65-103)
Hispanics
n
%
71 (65-101)
65-69
15,416
28.7
2,131
33.7
411
36.0
70-74
17,324
32.2
2,023
32.0
390
34.1
75-79
12,271
22.8
1,314
20.8
221
19.3
≥80
8,753
16.3
853
13.5
121
10.6
Total
53,764 100.0 6,321
100.0
1,143 100.0
Table 2. Comparison of tumor grades
among 3 racial/ethnic groups
Gleason Caucasians
Score
African
Americans
Hispanics
n
%
n
%
n
%
2-4
7,475
13.9
740
11.7
198
17.3
5-7
33,218 61.8 3,789
59.9
650
56.9
8-10
10,438 19.4 1,410
22.3
240
21.0
u/k
2,633
6.0
55
4.8
4.9
382
Table 3. Comparison of comorbidity
among 3 racial/ethnic groups
Comorbidity Caucasians
Scores
n
%
African
Americans
n
%
Hispanics
n
%
0
34,402 64.0 3,394 53.7
669
58.5
1
12,565 23.4 1,611 25.5
290
25.4
2
4,342
8.1
747
11.8
96
8.4
>=3
2,455
4.6
569
9.0
88
7.7
Table 4. Comparison of treatment
among 3 racial/ethnic groups
Surgery and
Radiation
Caucasians
African Am
Hispanics
n
%
n
%
n
%
Prostatectomy
Radiation
12,907
20,536
24.0
38.2
1,070
2,463
16.9
39.0
328
327
28.7
28.6
Both
1,205
2.2
89
1.4
26
2.3
Watchful Waiting
19,116
35.6
2,699
42.7
462
40.4
Chemotherapy
No
44,219
82.3
5,345
84.6
861
75.3
9,545
17.8
976
15.4
282
24.7
39,266
73.0
4,808
76.1
815
71.3
14,498
27.0
1,513
23.9
328
28.7
Yes
Hormone
No
Yes
Table 5. Comparison of socioeconomic
status (SES) among 3 ethnic groups
Poverty
(quartiles)
Caucasians
African Am
Hispanics
n
%
n
%
n
%
1st
14,861
27.6
267
4.2
69
6.0
2nd
14,429
26.8
529
8.4
132
11.6
3rd
13,974
26.0
838
13.3
208
18.2
4th
9,603
17.9
4639
73.4
693
60.6
897
1.7
48
0.8
41
3.6
100.0
1,143
100.0
Missing
Total
53,764 100.0 6,321
Table 8. Comparison of socioeconomic
status (SES) among 3 ethnic groups
Composite
SES (quartile)
(high to low)
Caucasians
Hispanics
%
n
%
n
%
1st (High SES) 14059
26.2
204
3.2
56
4.9
2nd
13732
25.5
460
7.3
121
10.6
3rd
13199
24.6
914
14.5
199
17.4
4th (Low SES)
9128
17.0
4528
71.6
661
57.8
Missing
3646
6.8
215
3.4
106
9.3
Total
n
African Am
53764 100.0 6321 100.0 1143 100.0
Table 9. Observed survival rate* by
ethnicity and socioeconomic status
Race/ethnicity
and SES
3-year survival (%)
(cases in 1992-1999)
5-year survival (%)
(cases in 1992-1997)
10-year survival (%)
(cases in 1992-1993)
All-cause
Diseasespecific
All-cause
Diseasespecific
All-cause
Diseasespecific
Caucasians
87.8
98.2
78.0
96.4
52.6
94.0
African Am
84.1
97.5
72.6
95.3
43.3
91.1
Hispanics
91.0
98.9
83.5
97.3
61.3
95.6
1st
90.6
98.7
82.5
97.2
58.6
94.9
2nd
88.3
98.1
79.1
96.3
53.9
93.9
3rd
86.9
98.3
76.4
96.3
50.5
94.0
4th
84.0
97.5
72.1
95.4
44.1
92.0
Total
87.5
98.2
77.5
96.3
51.9
93.7
Ethnic Groups
Composite SES
*unadjusted
Table 10. Hazard ratio of mortality
by socioeconomic status
SES
(high to low)
Hazard ratio (95% CI) of mortality*
All-cause mortality
CA-specific mortality
Model 1
Model 2
Model 3
Model 4
1.0 (ref)
1.0 (ref)
1.0 (ref)
1.0 (ref)
1.11
1.11
(1.07-1.16)
(1.07-1.16)
1.26
(1.09-1.44)
1.25
(1.09-1.44)
1.22
1.22
(1.17-1.27)
(1.17-1.27)
1.24
(1.07-1.43)
1.22
(1.05-1.41)
1.31
1.31
(1.25-1.36)
(1.25-1.37)
1.48
(1.28-1.70)
1.40
(1.20-1.64)
Composite SES
1st (High SES)
2nd
3rd
4th (Low SES)
*Models 1 & 3: adjusted for age, comorbidity, AJCC-stage, Gleason score, year of
diagnosis, SEER region, and treatment.
*Models 2 & 4: adjusted for race/ethnicity, in addition to factors in Models 1 & 3.
Table 12. Hazard ratio of mortality
by Poverty
SES
Hazard ratio (95% CI) of mortality*
All-cause mortality
CA-specific mortality
Model 1
Model 2
Model 3
Model 4
1st
1.0
1.0
1.0
1.0
2nd
1.11 (1.06-1.15)
1.11 (1.06-1.15)
1.17
(1.02-1.33)
1.15
(1.01-1.32)
3rd
1.19 (1.14-1.24)
1.19 (1.14-1.24)
1.12
(0.97-1.30)
1.11
(0.96-1.28)
4th
1.28 (1.23-1.34)
1.28 (1.22-1.34)
1.36
(1.18-1.55)
1.31
(1.13-1.52)
Poverty
*Models 1 & 3: adjusted for age, comorbidity, AJCC-stage, Gleason score, year
of diagnosis, SEER region, and treatment
*Models 2 & 4: adjusted for ethnicity, in addition to factors in Models 1 & 3.
Table 17. Hazard ratio of mortality
by race/ethnicity
Race/
ethnicity
Hazard ratio (95% CI) of mortality*
All-cause mortality
CA-specific mortality
Model 1
Model 2
Model 3
Model 4
1.00
1.00
1.00
1.00
1.14
1.01
1.33
1.17
(1.09-1.19)
(0.97-1.06)
0.85
0.78
(0.76-0.94)
(0.70-0.87)
Caucasians
African Am
Hispanics
(1.16-1.53) (0.99-1.37)
0.84
0.78
(0.57-1.24) (0.53-1.16)
* Models 1 & 3 - Adjusted for age, comorbidity, AJCC stage, Gleason score,
year of diagnosis, SEER region, and treatment.
* Models 2 & 4 - Adjusted for composite SES, in addition to above factors.
Further Analysis
• Apart from composite SES, the similar
results were achieved by controlling for
education, poverty, and income.
• There was no significant interaction
between race/ethnicity and
socioeconomic status.
Conclusions and
public health implications
• Racial disparity in survival among men with
locoregional prostate cancer was largely
explained by their socioeconomic status.
• Lower socioeconomic status appeared to be
one of the major barriers to achieving
comparable outcomes for men with prostate
cancer.
• Important public health implications if we are
to achieve the goals of Healthy People 2010,
one of which is to eliminate health disparities.
Strengths
• Large population-based cohort study, covering
all (>98%) incident cases of prostate Ca,
pathologically confirmed by the 11 SEER
registries.
• Reliable information on cancer stage, grade,
primary therapy (surgery and radiation), and
long-term follow-up on vital status.
• Linked with Medicare claims, providing
important data on comorbidity – a strong
confounder of survival.
• Adjuvant chemotherapy and hormonal therapy
data can be uniquely identified from Medicare
claims.
• Several measures of SES variables 
consistent findings.
Limitations
• SES at the level of census tract may be imperfect
proxy measure for individual SES  ecological
fallacy, but studies showed individual and
community level SESs in good agreement
• Local-regional stage  Residual confounding (even
after adjusting for AJCC stage and tumor grade
etc.)
• Hispanic ‘Paradox’ – low SES and RFs for mortality
but has mortality advantage
• Lack of info. on providers (physicians and
hospitals), on patient/physician preference on the
choice of the therapy, and on PSA screening and
surveillance
• Men age 65 or older, and in 11 SEER areas 
Generalizability to younger men and other regions
or country?
Questions/Comments
Thanks for your attention!