The Impact of Image Guided Radiation Therapy (IGRT) on Efficacy and Toxicity of Prostate Cancer: A Systematic Review and Meta-Analysis

Abstract

<h3>Purpose/Objective(s)</h3> Image-guided radiation therapy (IGRT) is widely used to correct prostate localization, but there have been no consistent conclusions regarding the effect of IGRT on the toxicity and survival in the absence of level 1 evidence. The purpose of this study is to perform a systematic review and meta-analysis of efficacy and toxicity of IGRT in prostate cancer. <h3>Materials/Methods</h3> A systematic review, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guide-lines, was conducted using PubMed, Embase, Medline databases and Cochrane Library databases until February 2022. Two investigators independently searched and selected literature, including randomized controlled trials (RCTs) and cohort studies (CRS). The data on efficacy and toxicity were extracted for quality assessment and meta-analysis to quantify the effect of IGRT on prostate-specific antigen (PSA) relapse-free survival, biochemical failure-free survival (BFFS), overall survival (OS), gastrointestinal (GI) toxicity and genitourinary (GU) toxicity. Heterogeneity assessment was performed using the <i>χ</i>² test and the <i>I</i>² statistic. Significant heterogeneity was indicated by <i>P</i> <0.05 in Cochrane Q tests and a ratio greater than 50% in <i>I</i>² statistics, which led to the use of random-effects models according to the DerSimonian and Laird method. <h3>Results</h3> The initial search strategy identified 2816 records in total, and 19 studies with 5186 patients met inclusion criteria after removing duplicates, screening, and full article review for the final meta-analysis. The results revealed that IGRT significantly reduced not only the grade 2 (G2) or worse (G2+) acute GI toxicity (risk ratio [RR] = 0.55 [95% confidence interval (CI), 0.36-0.85]; <i>P</i> = 0.007) and GU toxicity (RR = 0.82 [95% CI, 0.72-0.95]; <i>P</i> = 0.006), but also the G2+ late GI toxicity (hazard ratio [HR] = 0.25 [95% CI, 0.07-0.87]; <i>P</i> = 0.03) compared with non-IGRT. Moreover, IGRT significantly improved PSA relapse-free survival (HR = 0.43 [95% CI, 0.20-0.92]; <i>P</i> = 0.03). However, it was found that high frequency (once daily) IGRT took no advantage in BFFS (HR = 0.68 [95% CI, 0.41-1.12]; <i>P</i> = 0.13) and OS (HR = 1.34 [95% CI, 0.60-2.99]; <i>P</i> = 0.47) in prostate cancer than low frequency (once weekly or less) IGRT. <h3>Conclusion</h3> This is the first meta-analysis to demonstrate that IGTR control in prostate cancer significantly reduces G2+ acute GI and GU toxicity and improves PSA relapse-free survival. While it is important not to underestimate the negative effects on high frequency IGRT, which has little benefit on BFFS and OS.