PURPOSE: To determine if increasing the biologically equivalent dose (BED) via various radiation fractionation regimens is correlated with clinical outcomes or toxicities for prostate cancer.
METHODS AND MATERIALS: We performed a meta-analysis that included 12,756 prostate cancer patients from 55 studies published from 2003 to 2013 who were treated with non-dose-escalated conventionally fractionated external beam radiation therapy (non-DE-CFRT), DE-CFRT, hypofractionated RT, and high dose rate brachytherapy (HDR-BT; either mono or boost) with ⩾5-year actuarial follow-up. BEDs were calculated based on the following formula: (nd[1+d/(α/β)]), where n is the number of fractions, and d is dose per fraction; assuming an α/β of 1.5 for prostate cancer and 3.0 for late toxicities. Mixed effects meta-regression models were used to estimate weighted linear relationships between BED and the observed percentages of patients experiencing late toxicities or 5-year freedom from biochemical failure (FFBF).
RESULTS: Increases in 10Gy increments in BED (at α/β of 1.5) from 140 to 200Gy were associated with 5-unit improvements in percent FFBF. Dose escalation of BED above 200Gy was not correlated with FFBF. Increasing BED (at α/β of 3.0) from 98 to 133Gy was associated with increased gastrointestinal toxicity. Dose escalation above 133Gy was not correlated with toxicity.
CONCLUSIONS: An increase in the BED to 200Gy (at α/β of 1.5) was associated with increased disease control. Doses above 200Gy did not result in additional clinical benefit.
Written by:
Zaorsky NG, Palmer JD, Hurwitz MD, Keith SW, Dicker AP, Den RB. Are you the author?
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, USA; Department of Radiation Oncology, Sidney Kimmel Cancer Center at Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA; Department of Radiation Oncology, Sidney Kimmel Cancer Center at Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA; Department of Pharmacology and Experimental Therapeutics, Division of Biostatistics, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA.
Reference: Radiother Oncol. 2015 May 28. pii: S0167-8140(15)00246-7.
doi: 10.1016/j.radonc.2015.05.011
PubMed Abstract
PMID: 26028229
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