Long-term biochemical control of prostate cancer after standard or hyper-fractionation: Evidence for different outcomes between low-intermediate and high risk patients - Abstract

Prostate Program, Scientific Director's Office, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.

Radiation Oncology 1, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.

 

 

To report the long-term biochemical control of a non-randomized trial comparing standard (STD) and hyper-fractionated (HFX) radiation schedules for prostate cancer treatment.

Between 1993 and 2003, 370 patients entered the study; 330/370 (STD: 179; HFX: 151) were evaluable for current analysis. Median doses were 79.2Gy and 74Gy for HFX (1.2Gy/fr, two daily fractions) and STD (2Gy/fr), respectively; median follow-up was 7.5yr. The two regimens were compared in terms of biochemical relapse-free survival (according to ASTRO definition, bRFS) by univariate (log-rank test) and multivariate analyses (Cox regression hazard model). Based on published relationships between EQD2 and 5-yr biochemical control, α/β values for each subgroup could be estimated.

7.5yr bRFS were 53.4% (±4.4%, 95% CI) and 65.4% (±4.0%) for HFX and STD, respectively (p=0.13); HFX was associated with a poorer outcome in NCCN low+intermediate patients (7.5yr bRFS: 56.6% vs 73.5%, p=0.048) while no differences were seen for high-risk patients (7.5yr bRFS: 44.1% vs 45.3%). Multivariate analysis revealed that NCCN risk grouping (high vs low+intermediate; OR: 0.59, p=0.009) and age (< vs ⩾70yr; OR: 0.67, p=0.03) were the main predictors of worse bRFS. In the subgroups of low+intermediate-risk patients < 70yr, the poorer outcome of HFX was more evident (7.5yr bRFS: 47.1% vs 70.9%, p=0.078) while no difference was seen for older patients (7.5yr bRFS: 69.4% vs 72.0%, p=0.76). Our α/β estimates differ between low+intermediate-risk and high-risk patients.

The bRFS long-term results of this non-randomized trial are consistent with different sensitivities to fractionation depending on NCCN risk grouping. The impact of age on the outcome of HFX for younger low+intermediate patients is consistent with an incomplete repair effect in older patients.

Written by:
Valdagni R, Nahum AE, Magnani T, Italia C, Lanceni A, Montanaro P, Rancati T, Avuzzi B, Fiorino C.   Are you the author?

Reference: Radiother Oncol. 2011 Aug 26. Epub ahead of print.
doi: 10.1016/j.radonc.2011.07.017

PubMed Abstract
PMID: 21872954

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