Format

Send to

Choose Destination
See comment in PubMed Commons below
Med Dosim. 2014 Spring;39(1):12-7. doi: 10.1016/j.meddos.2013.08.007. Epub 2013 Oct 4.

Image-guided intensity-modulated radiotherapy for prostate cancer: Dose constraints for the anterior rectal wall to minimize rectal toxicity.

Author information

1
Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL. Electronic address: peterson.jennifer2@mayo.edu.
2
Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL.
3
Section of Biostatistics, Mayo Clinic Florida, Jacksonville, FL.
4
Section of Biostatistics, Mayo Clinic Florida, Jacksonville, FL; Department of Radiation Oncology, Southern Ohio Medical Center, Portsmouth, OH.

Abstract

Rectal adverse events (AEs) are a major concern with definitive radiotherapy (RT) treatment for prostate cancer. The anterior rectal wall is at the greatest risk of injury as it lies closest to the target volume and receives the highest dose of RT. This study evaluated the absolute volume of anterior rectal wall receiving a high dose to identify potential ideal dose constraints that can minimize rectal AEs. A total of 111 consecutive patients with Stage T1c to T3a N0 M0 prostate cancer who underwent image-guided intensity-modulated RT at our institution were included. AEs were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. The volume of anterior rectal wall receiving 5 to 80Gy in 2.5-Gy increments was determined. Multivariable Cox regression models were used to identify cut points in these volumes that led to an increased risk of early and late rectal AEs. Early AEs occurred in most patients (88%); however, relatively few of them (13%) were grade ≥2. At 5 years, the cumulative incidence of late rectal AEs was 37%, with only 5% being grade ≥2. For almost all RT doses, we identified a threshold of irradiated absolute volume of anterior rectal wall above which there was at least a trend toward a significantly higher rate of AEs. Most strikingly, patients with more than 1.29, 0.73, or 0.45cm(3) of anterior rectal wall exposed to radiation doses of 67.5, 70, or 72.5Gy, respectively, had a significantly increased risk of late AEs (relative risks [RR]: 2.18 to 2.72; p ≤ 0.041) and of grade ≥ 2 early AEs (RR: 6.36 to 6.48; p = 0.004). Our study provides evidence that definitive image-guided intensity-modulated radiotherapy (IG-IMRT) for prostate cancer is well tolerated and also identifies dose thresholds for the absolute volume of anterior rectal wall above which patients are at greater risk of early and late complications.

KEYWORDS:

Prostate; Radiotherapy; Toxicity

PMID:
24099966
DOI:
10.1016/j.meddos.2013.08.007
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center