Aspirin improves outcome in high risk prostate cancer patients treated with radiation therapy

Figures & data

Table 1. Patient characteristics compared with respect to major prognostic variables

Characteristic	Control	AC	P value
n =	29	45	N/A
Age (years)
Median	66	70	0.04
Range	49–84	53–86
Gleason score
6	3 (10.3%)	2 (4.4%)	0.52
7	8 (27.6%)	9 (20%)
8	8 (27.6%)	17 (38.8%)
9	8 (27.6%)	16 (35.6%)
10	2 (6.9%)	1 (2.2%)
Initial PSA
Mean	40	49	0.47
Median	30.9	21.6
Standard deviation	33	69.6
Range	4.7–147	1.8–332.7
Tumor clinical stage
T1c-T2b	14 (48.3%)	23 (51.1%)	0.81
T2c-T3b	14 (48.3%)	20 (44.4%)
Unknown	1 (3.4%)	2 (4.4%)
Follow-up (mo)
Mean	47	53.5	0.27
Median	51.3	61.6
Standard deviation	26	22.2
Range	3.2–88.3	1.9–81.9
Pelvic lymphatic irradiation
Yes	25 (86.2%)	40 (89.9%)	0.73
No	4 (13.8%)	5 (11.1%)
Hormone therapy
Yes	24 (82.8%)	40 (95.6%)	0.36
No	3 (10.3%)	2 (4.4%)
Duration of hormone therapy
None	3 (10.3%)	2 (4.4%)	0.25
<6 mo	4 (13.8%)	4 (8.9%)
6–23 mo	10 (34.4%)	12 (26.7%)
≥24 mo	10 (34.4%)	27 (60%)
Unknown	2 (6.9%)	0 (0%)

PSA, prostate specific antigen; AC, anticoagulant; P, P value.

Table 2. Univariate analysis of major prognostic factors and AC use with respect to 5-y FFBF, and OS

Variable	5-y BF %	HR	95% CI	P value	5-y OS%	HR	95% CI	P value
T-stage
T1c-T2b vs. T2c-T3b	19% vs. 32%	1.956	0.761–5.076	0.155	84% vs. 75%	1.624	0.562–4.688	0.365
Pelvic irradiation
Yes vs. no	25% vs. 22%	1.047	0.240–4.558	0.952	81% vs. 78%	1.262	0.282–5.654	0.761
Hormone deprivation
≤6 mo vs. >6 mo	8% vs. 27%	0.339	0.045–2.556	0.271	67% vs. 84%	2.714	0.833–8.842	0.084
Any AC use
Yes vs. no	20% vs. 38%	0.262	0.100–0.685	0.003	87% vs. 70%	0.410	0.142–1.186	0.089
Aspirin
Yes vs. no	16% vs. 35%	0.294	0.113–0.765	0.008	86% vs. 72%	0.444	0.154–1.282	0.123
Warfarin
Yes vs. no	22% vs. 25%	0.874	0.201–3.804	0.857	78% vs. 81%	1.227	0.273–5.513	0.789
Clopidogrel
Yes vs. no	12.5% vs. 26%	0.493	0.066–3.707	0.483	75% vs. 81%	1.345	0.142–1.186	0.698
Multiple AC use
Yes vs. no	21% vs. 25%	0.843	0.244–2.913	0.787	71% vs. 83%	1.626	0.511–5.237	0.402

HR, hazard ratio; CI, confidence interval; P, P value.

Figure 1. The effect of aspirin use on 5-y FFBF and OS. (A) Kaplan–Meier curve comparing FFBF in patients who took aspirin compared with those who did not. (B) Kaplan–Meier curve comparing OS in patients who took aspirin compared with those who did not. Solid line, patients who took aspirin; dashed line, patients who did not take aspirin.

Table 3. The effect of AC use on 5-y rates of distant metastasis

Variable	Distant metastasis %	HR	95% CI	P value
Any AC	11.6% vs. 28.6%	0.293	0.095–0.901	0.023
Aspirin	12.2% vs. 26.7%	0.325	0.106–0.998	0.039
Clopidogrel	0% vs. 20.6%	N/A	N/A	0.183
Warfarin	12.5% vs. 19%	0.694	0.089–5.387	0.726
Multiple agents	7.7% vs. 20.7%	0.351	0.045–2.712	0.294

Figure 2. Subgroup analysis comparing effect of aspirin on 5-y OS based upon GS. (A) Kaplan–Meier curve comparing OS with respect to aspirin use in GS ≤ 8 tumors. (B) Kaplan–Meier curve comparing OS with respect to aspirin use in GS 9–10 tumors. Solid line, patients who took aspirin; dashed line, patients who did not take aspirin.

Table 4A. Subset analysis of the effect of aspirin use in patients with GS 9–10 histologies

Variable	5-y OS%	HR	95% CI	P value
Age per year	N/A	1.162	1.102–1.327	0.027
Gleason score per unit	N/A	0	0.00–0.00	0.996
T-stage per unit	N/A	1.43	0.857–2.386	0.171
% cores positive	N/A	11.16	0.105–1184.064	0.311
Pelvic irradiation
Yes vs. no	70% vs. 100%	0	0.00–0.00	0.996
Hormone deprivation
≥24 mo vs. <24 mo	92% vs. 54%	0.133	0.016–1.112	0.063
N-stage
N0 vs. N1	75% vs. 67%	1.782	0.199–15.991	0.606
Aspirin
Yes vs. no	88% vs. 37%	0.165	0.032–0.853	0.0315

Univariate analysis on the effect of major prognostic variables and aspirin on 5-y OS

Table 4B. Subset analysis of the effect of aspirin use in patients with GS 9–10 histologies

Variable	5-y OS%	HR	95% CI	P value
Age per year	N/A	1.162	1.102–1.327	0.027
Gleason score per unit	N/A	0	0.00–0.00	0.996
T-stage per unit	N/A	1.43	0.857–2.386	0.171
% cores positive	N/A	11.16	0.105–1184.064	0.311
Pelvic irradiation
Yes vs. no	70% vs. 100%	0	0.00–0.00	0.996
Hormone deprivation
≥24 mo vs. <24 mo	92% vs. 54%	0.133	0.016–1.112	0.063
N-stage
N0 vs. N1	75% vs. 67%	1.782	0.199–15.991	0.606
Aspirin
Yes vs. no	88% vs. 37%	0.165	0.032–0.853	0.0315

Multivariate analysis of variables with P ≤ 0.1

Table 4C. Subset analysis of the effect of aspirin use in patients with GS 9–10 histologies

Variable	HR	95% CI	P value
Age	1.151	1.025–1.293	0.018
Aspirin use	0.113	0.019–0.676	0.017

Multivariate analysis of variables with P ≤ 0.05