Decreased acute toxicities of intensity-modulated radiation therapy for localized prostate cancer with prostate-based versus bone-based image guidance
Intensity-modulated radiation therapy (IMRT) is a major therapeutic option for localized prostate cancer. Image-guided radiation therapy (IGRT) allows tumor visualization and corrects the errors caused by daily internal movement of the prostate. The current study retrospectively compared the acute toxicities and biochemical tumor control outcomes of prostate IMRT achieved using two IGRT techniques: bony structure-based IGRT (B-IGRT) and prostate-based IGRT (P-IGRT).
Between February 2011 and July 2014, 96 patients with low- or intermediate-risk prostate cancer were treated using P-IGRT based on cone-beam computed tomography (CBCT; 76 Gy) without fiducial markers. This group of patients was compared with a similar cohort of 96 patients who were treated with B-IGRT (74 Gy) between July 2007 and September 2011. The planning target volume (PTV) margins were 1–3 mm smaller in the P-IGRT group than in the B-IGRT group.
The median follow-up periods for all patients, the P-IGRT group, and the B-IGRT group were 42, 32, and 64 months, respectively. A significantly lower incidence of acute grade 2 or higher gastrointestinal toxicities was observed in the P-IGRT group compared with the B-IGRT group (3 vs. 11%; p = 0.049). The prostate-specific antigen failure-free survival rates at 3 years were 95.5 and 92.7% for the P-IGRT and B-IGRT groups, respectively (p = 0.534).
IMRT with P-IGRT allows PTV margin reduction without sacrificing tumor control, which successfully reduces acute rectal toxicity compared with IMRT with B-IGRT.
KeywordsProstate cancer Intensity-modulated radiation therapy (IMRT) Image-guided radiation therapy (IGRT) Rectal toxicity
This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology, Japan (24591838 and 16K10390). The sponsor played no role in the study design; in the collection, analysis, and interpretation of the data; in the writing of the manuscript; or in the decision to submit this article for publication.
Compliance with ethical standards
Conflict of interest
Dr. Mizowaki receives a donation for research as the department representative from Mitsubishi Heavy Industries. The other authors report no conflict of interest with regard to this manuscript.
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