The role of rectal sparing devices in post-prostatectomy radiotherapy: a review article

Adjuvant or salvage radiotherapy can control biochemical relapse after radical prostatectomy and reduce the risk of distant metastases. Dose-escalated radiotherapy after radical prostatectomy can lead to improved biochemical relapse-free survival. Over the last decades, despite the technological advancements in prostate radiotherapy, radiation-induced rectal toxicity is still the main limiting factor for dose escalation owing to the anatomical proximity of the prostate gland to the rectum. To this end, several rectal sparing devices, including Endorectal balloons (ERBs), prostate-rectum spacers (e.g. SpaceOAR hydrogel), and rectal retractor have been explored to increase the distance between the prostate and the rectum to reduce rectal radiation doses and toxicities. Over the last decade, several studies applied these devices during post-prostatectomy radiotherapy setting. Therefore, the purpose of this review is to evaluate the impact of rectal sparing devices on dose-volume parameters of anorectal, radiation-induced rectal toxicity, and prostate bed motion during post-prostatectomy radiotherapy. The results showed that although using ERBs can lead to stability in the target volume position, it cannot reduce rectal radiation doses, in particular dose to the anterior rectal wall. The application of ERBs can reduce the received dose of the anal wall and increase the geometric reproducibility of the clinical target volume (CTV) position. However, the role of ERBs in reducing the received dose of the rectal wall is still controversial, which can be associated with the displacement of the anterior rectal wall towards the prostate bed (high radiation dose area). The use of SpaceOAR hydrogel can significantly increase the distance between the rectum and the prostate bed and ultimately reduce the dose received by the rectal wall. Also, the use of rectal retractor remarkably reduces rectal radiation doses. The dosimetric and clinical results of the use of SpaceOAR hydrogel and rectal retractor are very promising, and these devices can be used for patients after the necessary evaluations by radiation oncologist in post-prostatectomy radiotherapy. However, further studies will be required to elucidate the efficacy of SpaceOAR hydrogel and rectal retractor in reducing radiotherapy-induced rectal toxicity following post-prostatectomy radiotherapy. Keywords: prostatectomy, prostate cancer, radiotherapy, rectum

MMP-8 C-799T and MMP-8 C+17G polymorphisms in mild and severe preeclampsia: Association between MMP-8 C-799T with susceptibility to severe preeclampsia

Objective: The aim of present study was to determine the role of matrix metalloproteinase-8 (MMP-8) C-799T (rs11225395) and C+17 (rs2155052) polymorphisms in susceptibility to preeclampsia. Study design: In a case–control study, 256 pregnant women including 152 women with preeclampsia (86 women with mild preeclampsia and 66 women with severe preeclampsia) and 104 women with normal pregnancy from Western Iran with Kurdish ethnic background were investigated for MMP-8 C-799T and C + 17G polymorphisms using polymerase chain reaction-restriction fragment length polymorphism method. Results: Comparing the MMP-8 TT genotype with the combined genotype of CC+CT (recessive model) indicated a significantly higher frequency of the MMP-8 TT genotype (47%) in severe preeclamptic patients than that in healthy pregnant women (30.8%) that was associated with 1.99-fold increased risk of severe preeclampsia (95% CI = 1.05–3.77, p = 0.034). The frequency of MMP-8 G allele was 27.3% in all preeclamptic patients compared to 30.2% in controls (p = 0.56). Also, no significant difference was detected comparing the frequency of G allele in mild (26.6%, p = 0.46) and severe preeclamptic patients (28.4%, p = 0.75) with controls (30.2%). Conclusions: Our study demonstrated that the MMP-8 C-799T is associated with the risk of developing severe preeclampsia during pregnancy. However, the MMP-8 C + 17G polymorphism might not be a risk factor for susceptibility to preeclampsia