Definitive 3D-CRT for clinically localized prostate cancer: modifications of the clinical target volume following a prostate MRI and the clinical benefits

Abstract

PurposeTo evaluate the modifications of the tumor stage and clinical target volume following a prostate magnetic resonance imaging (MRI) to evaluate the tumor (T) staging, and the clinical benefits for prostate cancer.MethodsA total of 410 patients with newly diagnosed and clinically localized prostate cancer were retrospectively analyzed. The patients were treated with definitive three-dimensional conformal radiotherapy (3D-CRT). In all of the patients, digital rectal examination, transrectal ultrasound, prostate biopsy and computed tomography were performed to evaluate the clinical stage. Of the 410 patients, 189 patients had undergone a prostate MRI study to evaluate the T staging, and 221 patients had not.ResultsModification of the T stage after the prostate MRI was seen in 39 (25%) of the 157 evaluable patients, and a modification of the risk group was made in 14 (9%) patients. Eventually, a modification of the CTV in 3D-CRT planning was made in 13 (8%) patients, and 10 of these had extracapsular disease. Most of the other modifications of the T staging were associated with intracapsular lesions of prostate cancer which did not change the CTV. There were no significant differences in the biological relapse-free survival between the patients with and without a prostate MRI study.ConclusionsModification of the CTV were recognized in only 8% of the patients, most of whom had extracapsular disease, although that of the T stage was seen in approximately one-quarter of the patients. Prostate MRI should only be selected for patients with a high probability of extracapsular involvement.

Tumor staging using 3.0 T multiparametric MRI in prostate cancer: impact on treatment decisions for radical radiotherapy

“…This bias was minimised when quantitative parameters such as ADC or semi-quantitative ones such as time-intensity curves were analysed. In addition, this is common clinical practice and is assumed in most published studies on this matter (Panje et al 2015 ; Horsley et al 2015 ; Yamaguchi et al 2015 ; Chang et al 2014 ; Jackson et al 2005 ). Lastly, DRE/TRUS reliability was found to be very low in our study (8.8 %), and this could have influenced the elevated upstaging values observed with mpMRI.…”

“…Such variability can be due to several causes: some studies included patients who underwent MRI after starting HT treatment, leading to a reduction of tumour size and consequently a false downstaging (Panje et al 2015 ; Chang et al 2014 ); on the other hand, most of the studies in this context were performed using 1.5T MRI without endorectal coil (Panje et al 2015 ; Yamaguchi et al 2015 ; Chang et al 2014 ; Jackson et al 2005 ) whereas our investigation was conducted using 3T MRI, with higher diagnostic reliability (Park et al 2007 ). Morphological MRI has been used in most of the reported series without functional associated studies (Horsley et al 2015 ; Yamaguchi et al 2015 ; Chang et al 2014 ; Jackson et al 2005 ). Our study implemented the guide-recommended (Barentsz et al 2012 ) morphological T2 sequences along with two functional studies (DWI and DCE), increasing the diagnosis rate, as previously reported (Wu et al 2012 ; Verma et al 2012 ).…”

“…In particular, we observed a large number of patients initially categorized as cT1–T2a (239 patients), which might have contributed to such a marked degree of upstaging. On the other hand, in many of the aforementioned studies, HT was administered to all intermediate-risk patients (Panje et al 2015 ; Horsley et al 2015 ; Yamaguchi et al 2015 ; Chang et al 2014 ; Jackson et al 2005 ), independent of unfavourable risk factors. In this respect, if we had considered administering HT to all intermediate-risk patients, the impact of RT treatment would have decreased to 41.2 %.…”