Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
To investigate whether magnesium oxide during external-beam radiotherapy for prostate cancer reduces intrafraction prostate motion in a double-blind, placebo-controlled randomized trial.
At the Department of Radiotherapy, prostate cancer patients scheduled for intensity-modulated radiotherapy (77 Gy in 35 fractions) using fiducial marker-based position verification were randomly assigned to receive magnesium oxide (500 mg twice a day) or placebo during radiotherapy. The primary outcome was the proportion of patients with clinically relevant intrafraction prostate motion, defined as the proportion of patients who demonstrated in ≥50% of the fractions an intrafraction motion outside a range of 2 mm. Secondary outcome measures included quality of life and acute toxicity.
In total, 46 patients per treatment arm were enrolled. The primary endpoint did not show a statistically significant difference between the treatment arms with a percentage of patients with clinically relevant intrafraction motion of 83% in the magnesium oxide arm as compared with 80% in the placebo arm (p = 1.00). Concerning the secondary endpoints, exploratory analyses demonstrated a trend towards worsened quality of life and slightly more toxicity in the magnesium oxide arm than in the placebo arm; however, these differences were not statistically significant.
Magnesium oxide is not effective in reducing the intrafraction prostate motion during external-beam radiotherapy, and therefore there is no indication to use it in clinical practice for this purpose.
Written by:
Lips IM, van Gils CH, Kotte AN, van Leerdam ME, Franken SP, van der Heide UA, van Vulpen M. Are you the author?
Reference: Int J Radiat Oncol Biol Phys. 2011 Nov 16. Epub ahead of print.
doi: 10.1016/j.ijrobp.2011.07.030
PubMed Abstract
PMID: 22099039
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