Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma, Japan.
To determine the predictive risk factors for Grade 2 or worse rectal bleeding after high-dose-rate brachytherapy (HDR-BT) combined with hypofractionated external-beam radiotherapy (EBRT) for prostate cancer using dose-volume histogram analysis.
The records of 216 patients treated with HDR-BT combined with EBRT were analyzed. The treatment protocols for HDR-BT were 5 Gy × five times in 3 days or 7 Gy × three, 10.5 Gy × two, or 9 Gy × two in 2 days. The EBRT doses ranged from 45 to 51 Gy with a fractional dose of 3 Gy.
In 20 patients Grade 2 or worse rectal bleeding developed, and the cumulative incidence rate was 9% at 5 years. By converting the HDR-BT and EBRT radiation doses into biologic effective doses (BED), the BED(3) at rectal volumes of 5% and 10% in the patients who experienced bleeding were significantly higher than those in the remaining 196 patients. Univariate analysis showed that a higher rectal BED(3-5%) and the use of fewer needles in brachytherapy were correlated with the incidence of bleeding, but BED(3-5%) was found to be the only significant factor on multivariate analysis.
The radiation dose delivered to small rectal lesions as 5% is important for predicting Grade 2 or worse rectal bleeding after HDR-BT combined with EBRT for prostate cancer.
Written by:
Okamoto M, Ishikawa H, Ebara T, Kato H, Tamaki T, Akimoto T, Ito K, Miyakubo M, Yamamoto T, Suzuki K, Takahashi T, Nakano T. Are you the author?
Reference: Int J Radiat Oncol Biol Phys. 2011 May 26. Epub ahead of print.
doi: 10.1016/j.ijrobp.2011.03.041
PubMed Abstract
PMID: 21620579
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