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Increasing Radiation Doses Decrease Local and Distant Failures in Patients With Localized Prostate Cancer
I. J. Radiation Oncology d Biology d Physics
S332
Volume 69, Number 3, Supplement, 2007
The frequency of ARWDs ARWD (mm)
. 10%
Initial 10 pts Additional 40 pts
0 0.15
7 to
10%
0.85 2.1
5 to 1.4 4.3
6%
4 to 0% 17 40.2
1 to 5%
6 to 10%
.10%
Corrections RF%
Total CBCTs
42.6 46.9
23.3 5.7
14.7 0.7
8.8 4
352 1300
Author Disclosure: D.G. Pradhan, None; R. Hammoud, None; K. LaMoria, None; Y. Xu, None; L. Aquilina, None; J. Kim, None; H. Guan, None; S. Kowalsky, None; M. Ajlouni, None; B. Movsas, None.
2233
Increasing Radiation Doses Decrease Local and Distant Failures in Patients With Localized Prostate Cancer
C. A. Reddy1, E. A. Klein1, A. Mahadevan1, P. A. Kupelian2 1
Cleveland Clinic Foundation, Cleveland, OH, 2MD Anderson Cancer Center Orlando, Orlando, FL
Purpose/Objective(s): To study the potential impact of radiation (RT) dose on local failures and distant metastases in localized prostate cancer patients treated with external beam radiotherapy. Materials/Methods: Between 1986 and 2000, 919 patients with clinical stage T1-3N0M0 adenocarcinoma of the prostate were treated with RT and no androgen deprivation (AD). The RT doses delivered were with standard fractionation (1.8 to 2.0 Gy per fraction) in 767 cases to doses ranging from 60–78 Gy, and with hypofractionation (70 Gy delivered at 2.5 Gy per fraction) in 152 cases. Seventy Gy at 2.5 Gy per fraction is equivalent to approximately 83 Gy at 2.0 Gy per fraction for prostate cancer tissues, according to the LQ model if an alpha/beta ratio of 1.8 is used. A high-dose hypofractionated schedule is therefore a method of dose-escalation. Three separate dose groups were analyzed: \72 Gy (n = 552, median dose 68.4 Gy), $72 \ 82 Gy (n = 215, median dose 78 Gy), and $82 Gy (n = 152, median dose 83 Gy). The median follow-up for all cases was 97 months. The median follow-up periods for patients receiving \72 Gy, $72\82 Gy, and $82 Gy were 112, 94 and 65 months, respectively. The analysis endpoints were distant metastasis (DM) and local failures (LF: defined as positive biopsies or clinical presentation). A total of 332 cases (36%) had biochemical failure (bF) (nadir+2) by the last follow-up. The proportions of bF were 50%, 22% and 5% for patients receiving \72 Gy, $72\82 Gy, and $82 Gy, respectively. A total of 238 cases (26%) received therapy (mostly AD) at one point after bF. Results: For all patients, the LF rate at 10 and 15 years were 6% and 13%, respectively. The 7 year LF rates for \72 Gy, $72\82 Gy, and $82 Gy were 6% vs 2% vs. 2%, respectively (p = 0.012, Fig. 1). For all patients, the DM rates at 10 and 15 years were 10% and 17%, respectively. The 7 year DM rates for \72 Gy, $72\82 Gy, and $82 Gy were 9% vs 6% vs. 1%, respectively (p = 0.008). As seen in Fig. 1, it is clear that for patients receiving \72 Gy, local and distant failures occurred eyond 10 years. Multivariate time-to-failure analysis using the Cox proportional hazards model was performed using the following parameters: T-stage (T1-T2A vs T2B-T2C vs T3), iPSA, bGS, and RT dose (continuous variable). For all cases, the multivariate analysis revealed T-stage (p \ 0.001), iPSA (p = 0.001), bGS (p \ 0.001), and RT dose (p = 0.032), to be predictors of DM. For all cases, the multivariate analysis revealed only bGS (p = 0.003), and RT dose (p = 0.004), to be predictors of LF. Conclusions: Although the impact of increasing RT doses has been mostly documented on bF rates, there is a clear association between higher RT doses, lower LF rates, and lower DM rates.
Author Disclosure: C.A. Reddy, None; E.A. Klein, None; A. Mahadevan, None; P.A. Kupelian, None.
S332
Volume 69, Number 3, Supplement, 2007
The frequency of ARWDs ARWD (mm)
. 10%
Initial 10 pts Additional 40 pts
0 0.15
7 to
10%
0.85 2.1
5 to 1.4 4.3
6%
4 to 0% 17 40.2
1 to 5%
6 to 10%
.10%
Corrections RF%
Total CBCTs
42.6 46.9
23.3 5.7
14.7 0.7
8.8 4
352 1300
Author Disclosure: D.G. Pradhan, None; R. Hammoud, None; K. LaMoria, None; Y. Xu, None; L. Aquilina, None; J. Kim, None; H. Guan, None; S. Kowalsky, None; M. Ajlouni, None; B. Movsas, None.
2233
Increasing Radiation Doses Decrease Local and Distant Failures in Patients With Localized Prostate Cancer
C. A. Reddy1, E. A. Klein1, A. Mahadevan1, P. A. Kupelian2 1
Cleveland Clinic Foundation, Cleveland, OH, 2MD Anderson Cancer Center Orlando, Orlando, FL
Purpose/Objective(s): To study the potential impact of radiation (RT) dose on local failures and distant metastases in localized prostate cancer patients treated with external beam radiotherapy. Materials/Methods: Between 1986 and 2000, 919 patients with clinical stage T1-3N0M0 adenocarcinoma of the prostate were treated with RT and no androgen deprivation (AD). The RT doses delivered were with standard fractionation (1.8 to 2.0 Gy per fraction) in 767 cases to doses ranging from 60–78 Gy, and with hypofractionation (70 Gy delivered at 2.5 Gy per fraction) in 152 cases. Seventy Gy at 2.5 Gy per fraction is equivalent to approximately 83 Gy at 2.0 Gy per fraction for prostate cancer tissues, according to the LQ model if an alpha/beta ratio of 1.8 is used. A high-dose hypofractionated schedule is therefore a method of dose-escalation. Three separate dose groups were analyzed: \72 Gy (n = 552, median dose 68.4 Gy), $72 \ 82 Gy (n = 215, median dose 78 Gy), and $82 Gy (n = 152, median dose 83 Gy). The median follow-up for all cases was 97 months. The median follow-up periods for patients receiving \72 Gy, $72\82 Gy, and $82 Gy were 112, 94 and 65 months, respectively. The analysis endpoints were distant metastasis (DM) and local failures (LF: defined as positive biopsies or clinical presentation). A total of 332 cases (36%) had biochemical failure (bF) (nadir+2) by the last follow-up. The proportions of bF were 50%, 22% and 5% for patients receiving \72 Gy, $72\82 Gy, and $82 Gy, respectively. A total of 238 cases (26%) received therapy (mostly AD) at one point after bF. Results: For all patients, the LF rate at 10 and 15 years were 6% and 13%, respectively. The 7 year LF rates for \72 Gy, $72\82 Gy, and $82 Gy were 6% vs 2% vs. 2%, respectively (p = 0.012, Fig. 1). For all patients, the DM rates at 10 and 15 years were 10% and 17%, respectively. The 7 year DM rates for \72 Gy, $72\82 Gy, and $82 Gy were 9% vs 6% vs. 1%, respectively (p = 0.008). As seen in Fig. 1, it is clear that for patients receiving \72 Gy, local and distant failures occurred eyond 10 years. Multivariate time-to-failure analysis using the Cox proportional hazards model was performed using the following parameters: T-stage (T1-T2A vs T2B-T2C vs T3), iPSA, bGS, and RT dose (continuous variable). For all cases, the multivariate analysis revealed T-stage (p \ 0.001), iPSA (p = 0.001), bGS (p \ 0.001), and RT dose (p = 0.032), to be predictors of DM. For all cases, the multivariate analysis revealed only bGS (p = 0.003), and RT dose (p = 0.004), to be predictors of LF. Conclusions: Although the impact of increasing RT doses has been mostly documented on bF rates, there is a clear association between higher RT doses, lower LF rates, and lower DM rates.
Author Disclosure: C.A. Reddy, None; E.A. Klein, None; A. Mahadevan, None; P.A. Kupelian, None.