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Because this was a nonrandomized clinical trial, we
performed a second sensitivity analysis using propensity
score adjustment as an alternative method to account for
pretreatment differences between patients receiving dif-
ferent treatments. After propensity score adjustment, we
did not note any substantial differences from our primary
results.
4.
Discussion
In this prospective, longitudinal, population-based study of
functional outcomes after contemporary prostate cancer
treatment, we observed that the effect of treatment on
patient-reported function did not vary dramatically by race/
ethnicity. Only for the urinary incontinence domain did we
find any evidence of a significant interaction between race
and prostate cancer treatment. AA men experienced a more
pronounced post-RP decline in scores for urinary inconti-
nence compared to white men, but the corresponding
changes in bother scores were not significantly different
between the races. We also found that race/ethnicity is not
nearly as predictive of function at 1 yr as treatment
selection and baseline function. These findings are new to
the prostate cancer literature and will be leveraged to
inform patient-facing, web-based treatment decision aids
for men considering treatment for localized prostate cancer.
Only one other study has examined the interaction
between race/ethnicity and treatment on functional out-
comes after prostate cancer treatment. In PCOS, the authors
likewise demonstrated a significant interaction between
race/ethnicity and urinary incontinence
[8] .However, in
that study, AA men reported better domain scores for
urinary incontinence after RP compared to white men. By
contrast, AAmen in the current study reported worse effects
of RP with respect to urinary incontinence compared to
white men. While the precise reason for this difference
between the studies is unknown, we speculate that there
may be several plausible explanations. First, compared to
the PCOS era, there is now widespread utilization of
minimally invasive RP, IMRT, and image-guided radiation
therapy. These newer approaches may affect men of
different races differently compared to older treatments.
This is supported in part by the findings from the sensitivity
analysis, which showed that the race-treatment interaction
seemed to be even stronger among patients who received
robotic surgery or IMRT. Second, it is important to recognize
that the original PCOS did not study AS patients. Having an
AS cohort allowed us to estimate treatment effects
Table 3 – Adjusted mean difference in function at 12 mo between treatment types by race/ethnicity
Adjusted mean difference between treatment types
Differences in treatment effect
White
AA
Hispanic
White vs AA
White vs Hispanic
D
(95% CI)
D
(95% CI)
D
(95% CI)
DID (95% CI)
DID (95% CI)
Irritative
EBRT vs AS
1.8 ( 0.5 to 4.1)
1.2 ( 5.2 to 2.8)
1.6 ( 4.5 to 7.8)
3.0 ( 1.0 to 7.0)
0.2 ( 5.9 to 6.2)
RP vs AS
3.8 (1.8 to 5.7)
y
0.6 ( 4.2 to 2.9)
0.3 ( 4.3 to 4.9)
4.4 (0.8 to 8.0)
y
3.5 ( 1.0 to 8.0)
RP vs EBRT
2.0 (0.2 to 3.7)
y
0.6 ( 2.9 to 4.1)
1.4 ( 6.4 to 3.7)
1.4 ( 2.0 to 4.8)
3.3 ( 1.8 to 8.5)
Incontinence
EBRT vs AS
2.4 ( 0.5 to 5.4)
2.4 ( 8.1 to 3.2)
5.9 ( 2.5 to 14.3)
4.9 ( 0.7 to 10.4)
3.5 ( 11.8. 4.8)
RP vs AS
18.6 ( 21.4 to 15.8) *
27.0 ( 33.4 to 20.6) *
19.8 ( 28.0 to 11.6) *
8.4 (2.0 to 14.8)
y
1.3 ( 7.0 to 9.5)
RP vs EBRT
21.0 ( 23.8 to 18.3) *
24.5 ( 30.5 to 18.6) *
25.8 ( 32.7 to 18.9) *
3.5 ( 2.5 to 9.5)
4.7 ( 2.0 to 11.5)
Bowel
EBRT vs AS
2.9 ( 5.1 to 0.8) *
3.6 ( 7.8 to 0.7)
0.7 ( 5.4 to 4.0)
0.6 ( 3.8 to 5.0)
2.3 ( 6.9 to 2.3)
RP vs AS
1.3 ( 0.3 to 2.9)
1.7 ( 2.0 to 5.4)
0.8 ( 5.0 to 3.4)
0.4 ( 4.2 to 3.4)
2.0 ( 2.1 to 6.1)
RP vs EBRT
4.2 (2.5 to 5.9)
y
5.3 (2.3 to 8.2) *
0.1 ( 3.7 to 3.5)
1.1 ( 4.0 to 1.9)
4.3 (0.7
[3_TD$DIFF]
to 7.8)
y
Sexual
EBRT vs AS
6.8 ( 11.0 to 2.6) *
6.0 ( 14.0 to 1.9)
5.0 ( 16.0 to 6.0)
0.8 ( 8.8 to 7.1)
1.9 ( 12.7 to 9.0)
RP vs AS
28.8 ( 32.5 to 25.1) *
28.6 ( 36.0 to 21.1) *
26.5 ( 36.1 to 17.0) *
0.2 ( 7.7 to 7.3)
2.3 ( 11.7 to 7.2)
RP vs EBRT
21.9 ( 25.4 to 18.5) *
22.5 ( 29.0 to 16.0) *
21.5 ( 30.8 to 12.3) *
0.6 ( 5.9 to 7.1)
0.4 ( 9.6 to 8.8)
AA = African American;
D
= difference; CI = confidence interval; DID = difference in difference; EBRT = external beam radiotherapy; AS = active surveillance;
RP = radical prostatectomy.
*
p
<
0.05.
Table 2 – Pretreatment function quartiles by race/ethnicity.
y
White (
n
= 1835)
AA (
n
= 324)
Hispanic (
n
= 179)
p
value
Urinary irritative
88 (75–100)
88 (75–100)
81 (62–94)
0.013
Urinary incontinence
100 (85–100)
100 (73–100)
94 (68–100)
<
0.001
Bowel function
100 (96–100)
100 (88–100)
100 (88–100)
0.003
Sexual function
75 (38–90)
67 (22–90)
65 (27–85)
<
0.001
Data are presented as median (interquartile range).
AA = African-American.
E U R O P E A N U R O L O G Y 7 2 ( 2 0 1 7 ) 3 0 7 – 3 1 4
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