Prostate Cancer
Table 2: Low-dose-rate Brachytherapy – Clinical Results for Patients with Low-risk Prostate Cancer Author
Number of Patients PSA Relapse Definition Median Follow-up Ellis et al.89
Zelefsky et al.90 Zelefsky et al.46 Block et al.91
Khaksar et al.58 Guedea et al.92 Stock et al.52 Prada et al.93 Potters et al.59 Sharkey et al.94 Cosset et al.25
Joseph et al.95
Critz and Levinson53 Bladou et al.96
Battermann et al.97 D’Amico et al.98 Sylvester et al.99 Kwok et al.100 Grimm et al.62 Wallner et al.35 Martin et al.101 Merrick et al.102
239 367
2,693 114 300 241 589 275 481
1,707 809
667
1,469 177 114 196 73 41
125 126 273 273
ASTRO ASTRO ASTRO ASTRO ASTRO ASTRO ASTRO ASTRO
ASTRO-Kattan ASTRO ASTRO
ASTRO 0.2 ng/ml
Not defined ASTRO ASTRO
Two PSA rises ASTRO
Two PSA rises >0.5 ng/ml Houston ASTRO
47 months 63 months 63 months 49 months 45 months 30 months 3.8 years 31 months 82 months – –
31 months 6 years
29 months 48 months 4 years
63 months 7 years
81 months 2.9 years 5 years
31 months Years after Diagnosis
7 5 8 5 5 3
10 5
12 12 5
8
10 3 5 5
10 5
10 3
12 5
ABS = American Brachytherapy Society; ASTRO = American Society for Therapeutic Radiology and Oncology; PSA = prostate-specific antigen. Source: Koukourakis et al., 2009.103
Figure 5: Prostate-specific Antigen Relapse-free Survival Categorised by Post-treatment Prostate Specific Antigen Nadir Value in Patients with Prostate Cancer Eight Years after Low-dose-rate Brachytherapy Treatment
100
80 90
70 60
10 20 30 40 50
0 0–0.49
PSA = prostate-specific antigen. Source: Zelefsky et al., 2007.46
Clinical Outcomes of Low-dose-rate Prostate Brachytherapy
Measuring Outcomes in Prostate Cancer – Prostate-specific Antigen
Pre-BT treatment PSA serum levels are major prognostic criteria. Lower recurrence rates have been correlated with low pre-treatment PSA serum levels. For example, a retrospective study of patients treated with LDR BT observed recurrence rates of 0 % at PSA levels of ≤4 ng/ml, but these progressively increased to 58 % at levels of 20.1–50 ng/ml.45
This trend is supported by the results from a further study of patients with clinically localised PCa that also identified a survival correlation with pre-implant PSA serum levels. This was a five-year follow-up in which the recurrence-free survival in PCa decreased with increasing baseline PSA levels.19
78 0.5–0.99 1.0–1.99 PSA nadir value (ng/ml) ≥2.0
As well as its utility in pre-treatment screening, the PSA assay provides a rapid, objective evaluation of the results of the various treatments.19 In several series, the post-implant PSA nadir was found to be the most significant predictive factor associated with disease-free survival. A PSA nadir ≤0.5 ng/ml can be considered to be an indicator of recurrence-free survival at 10 years.
The clinical progression rate was 3, 50 or 100 % in patients with one-year post-implant PSA serum levels of ≤1, 1–4 or >4 ng/ml, respectively. After a median 30-month follow-up, the local control rate was 97 % and recurrence-free survival at five years was 76 %.45
The outcome of LDR BT in PCa also correlates with the post-treatment PSA nadir. In the retrospective trial that identified a correlation between pre-treatment PSA levels and outcome, PSA serum levels at one year after implantation were shown to correlate with clinical progression rates.45
More
recently, in a multi-institutional analysis of long-term data for LDR BT, the eight-year PSA relapse-free survival was seen to decrease as PSA nadir values increased (see Figure 5).46
In a further trial, Critz
et al. observed that in patients treated with radiotherapy for PCa, the proportion of disease-free surviving patients who had a PSA nadir ≤0.5 ng/ml was 95 % at five years and the proportion at 10 years was 84 %. Disease-free survival, however, fell dramatically to 29 % at five years if the PSA nadir was between 0.6 and 1 ng/ml.47
It is important to note that PSA levels have been shown to increase temporarily after implantation, without a clear explanation. This seems to occur in 30–40 % of patients without signalling cancer recurrence.48,49 This phenomenon, called ‘PSA bounce’, was first described by Wallner et al. in the late 1990s.50
The median time to PSA bounce is 18 months
from the time of implant and 92 % of bounces were observed within 36 months. Occasionally, a patient’s PSA bounce may reach serum levels higher than the pre-implantation level; nevertheless, bounce has
EUROPEAN UROLOGICAL REVIEW
96 96 82
94.7 96 93 94 96 89 89
ABS: 97 % Non-ABS: 94 % 84.3 93 98 89 95 89 85 87
89–91 90 97
Percentage Biochemical-free Recurrence
PSA-relapse-free survival (%)
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