HDR boost best if biological equivalent dose 1.5>104 Gv

[JimmyToowong]

Int J Med Sci. 2008 Jun 4;5(3):113-20.

The relationship between the biochemical control outcomes and the quality of planning of high-dose rate brachytherapy as a boost to external beam radiotherapy for locally and locally advanced prostate cancer using the RTOG-ASTRO Phoenix definition.

Pellizzon AC, Salvajoli J, Novaes P, Maia M, Fogaroli R, Gides D, Horriot R.

Radiation Oncology Department, Hospital A C Camargo, Sao Paulo, Brazil. cassiopellizzon@aol.com

Abstract

PURPOSE: To evaluated prognostic factors and impact of the quality of planning of high dose rate brachytherapy (HDR-BT) for patients with local or locally advanced prostate cancer treated with external beam radiotherapy (EBRT) and HDR-BT. METHODS AND MATERIALS: Between 1997 and 2005, 209 patients with biopsy proven prostate adenocarcinoma were treated with localized EBRT and HDR-BT at the Department of Radiation-Oncology, Hospital A. C. Camargo, Sao Paulo, Brazil. Patient's age, Gleason score (GS), clinical stage (CS), initial PSA (iPSA), risk group for biochemical failure (GR), doses of EBRT and HDR-BT, use of three-dimensional planning for HDR-BT (3DHDR) and the Biological Effective Dose (BED) were evaluated as prognostic factors for biochemical control (bC).

RESULTS: Median age and median follow-up time were 68 and 5.3 years, respectively. Median EBRT and HDR-BT doses were 45 Gy and 20 Gy. The crude bC at 3.3 year was 94.2%. For the Low, intermediate and high risk patients the bC rates at 3.3 years were 91.5%, 90.2% and 88.5%, respectively. Overall survival (OS) and disease specific survival rates at 3.3 years were 97.8% and 98.4%, respectively. On univariate analysis the prognostic factors related bC were GR (p= 0.040), GS < or = 6 (p= 0.002), total dose of HDR-BT > or = 20 Gy (p< 0.001), 3DHDR (p< 0.001), BED-HDR > or = 99 Gy(1.5) (p<0.001) and BED-TT > or = 185 (p<0.001). On multivariate analysis the statistical significant predictive factors related to bC were RG (p< 0.001), HDR-BT > or = 20 Gy (p=0.008) and 3DHDR (p<0.001).

CONCLUSIONS: we observed that the bC rates correlates with the generally accepted risk factors described in the literature. Dose escalation, evaluated through the BED, and the quality of planning of HDR-BT are also important predictive factors when treating prostate cancer.

{jm: BED-HDR(1.5) = 104 Gy, BED-TT(1.5) = 211 Gy}

PMID: 18566673 Forum: Other prostate cancer topics including radiation Title: HDR brachy boost best if biological equivalent dose (1.5) >104 Gy

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