Evaluation of the optimal field arrangement for conformal radiotherapy for prostate cancer patients

Objective:The aim of this study was to evaluate the optimal field arrangement for conformal radiotherapy (CFRT) for prostate cancer patients.Methods:Thirty patients with prostate cancer of different grades and stages were treated with 3D conformal radiotherapy to minimize the dose to bladder,rectum and head of both femora using four fields (4F),five fields (5F),six fields (6F) and ARC techniques to minimize the risk of over dose to bladder,rectum and femoral heads.Patients received a total dose between 76 to 78 Gy given in 38 to 39 fractions over 7.5 to 8 weeks.Results:It was observed that V95,D95,D50 and D5 values for planning target volume (PTV) were comparatively higher when planned by 5 fields technique than when planned by fixed field technique (91%,91%,90% and 91.4% for skip-scan technique versus 85%,87%,86% and 88% by fixed field).The organs like rectum and urinary bladder get much higher dose when treated by fixed field techniques than rotation or 5 fields technique,when comparison was made for V95,V50 and DM values for rectum and urinary bladder obtained by 5 fields technique planning and 4/6 field planning,the value for 5 fields technique was found to be lower than 4/6 field technique (1%,70% and 51% versus 13%,91% and 55% for rectum and 4%,25% and 51% versus 16%,38% and 56% for urinary bladder respectively).Conclusion:Similarly for femoral heads,planning by full rotational technique had been observed to be beneficial as compared to when planning was done by fixed field technique (0%,0% and 29% versus 0%,1% and 28%).

Application of three dimensional conformal radiation therapy combined with high-intensity focused ultrasound for prostate cancer

Objective:Prostate cancer is a form of cancer that develops in the prostate,a gland in the male reproductive system.Prostate cancer tends to develop in men over the age of fifty;it is one of the most prevalent types of cancer in men.This article introduced a new method of prostate cancer treatment with the combination of three dimensional conformal radiation therapy (3D-CRT) and high-intensity focused ultrasound (HIFU),its efficacy was evaluated.Methods:From January 2004 to December 2009,95 patients were diagnosed with prostate cancer,among them,48 patients were received combined therapy with total irradiation of TD 60 Gy/30 Fx and 5 fractions of HIFU treatment,while 47 patients were received with pure 3D-CRT with total irradiation of TD (66-72) Gy/(33-36) Fx.Various indicators were evaluated,such as the local control rate and distant metastasis rate,the changes in blood PSA and fPSA,changes in T-lymphocyte subsets and NK cells,as well as acute adverse reaction of normal tissue.Results:The local response rate difference between the two groups had statistical significance (P < 0.05);the changes in blood PSA and fPSA were significant (P < 0.05);CD3+,CD4+,CD8+,CD4+/CD8+ and NK cells of the combined group increased obviously (P < 0.01),while the latter group had no increase (P > 0.05);the combined group had lower blood cells reduction and II-level acute adverse reaction of rectum,bladder and caput humeri than the pure group,but the II-level acute adverse reaction of urogenital canal in the combined group was higher (P < 0.05).Conclusion:The combined therapy with 3D-CRT and HIFU is a good way for the treatment of aged-related prostate cancer.It can ease the symptoms,control the disease and lengthen the survival time.

A meta-analysis for assessing the value of MR spectroscopy in the diagnosis of prostate cancer

Objective： To assess the value of MR spectroscopy （MRS） in the diagnosis of prostate cancer by meta-analysis. Methods： Prospective studies were selected from the MEDLINE, Ovid, Embase databases, Springer, Elsevier, China National Knowledge Infrastructure. According to the suggestion, results were determined by the ratio of （Cho＋Cr）/Cit. If this ratio was less than 0.75, negative result was respectively determined, and the definitive tumor was diagnosed as this threshold. According to the assessment standard of Evidence-based Medicine, English and Chinese literature in Grade A and B on MRS imaging was included. According to homogeneity test, different effect models were chosen to calculate different pooled weighted values of sensitivity, specificity and the corresponding 95% confidence intervals （95% CI）. Summary receiver operating characteristic （SROC） curves were used to assess the results. Funnel plot was used to analyze publication bias. Results： According to the assessment standard of Evidence-based Medicine, only 5 papers in Grade B were included in this research. The pooled weighted sensitivity and its 95% confidence interval is 82% （73%, 89%） and the pooled weighted sensitivity and its 95% confidence interval is 68% （58%, 76%）. The AUC （area under curve） is 83.40%. An asymmetric funnel plot suggested two missing studies leading to publication bias. Conclusion： If the ratio of （Cho＋Cr）/Cit is regarded as the diagnostic criteria in detecting prostate cancer by MRS, meta-analysis suggests this method has a better diagnostic value to detect the malignant prostate mass but the sensitivity needs to be improved. We hope to support a method and requirement about diagnostic test. Performing perspective register and improving quality of study design is the only way to reduce the bias and get real information of disease.

Evaluating the influence of 6 MV and 15 MV photon beams on prostate intensity-modulated radiation therapy plans

Objective We aimed to determine the ef ects of low- and high-energy intensity-modulated radiation therapy （IMRT） photon beams on the target volume planning and on the critical organs in the case of prostate can-cer. Methods Thirty plans were generated by using either 6 MV or 15 MV beams separately, and a combination of both 6 and 15 MV beams. Al plans were generated by using suitable planning objectives and dose con-straints, which were identical across the plans, except the beam energy. The plans were analyzed in terms of their target coverage, conformity, and homogeneity, regardless of the beam energy. Results The mean percentage values of V70 Gy for the rectal wal for the plans with 6 MV, 15 MV, and mixed-energy beams were 16.9%, 17.8%, and 16.4%, respectively, while the mean percentage values of V40 Gy were 53.6%, 52.3%, and 50.4%. The mean dose values to the femoral heads for the 6 MV, 15 MV, and mixed-en-ergy plans were 30.1 Gy, 25.5 Gy, and 25.4 Gy, respectively. The mean integral dose for the 6 MV plans was 10% larger than those for the 15 MV and mixed-energy plans.Conclusion These preliminary results suggest that mixed-energy IMRT plans may be advantageous with respect to the dosimetric characteristics of low- and high-energy beams. Although the reduction of dose to the organs at risk may not be clinical y relevant, in this study, IMRT plans using mixed-energy beams exhibited better OAR sparing and overal higher plan quality for deep-seated tumors.

两套TPS之间VMAT计划优化质量评价研究

目的探讨两套商用TPS实施VMAT优化的性能特点。方法随机选取本院宫颈癌和前列腺癌患者各10例，分别利用瓦里安Eclipse和飞利浦Pinnacle TPS设计VMAT计划（宫颈癌2Arc、3Arc。前列腺癌1Arc、2Arc），采用瓦里安Clinac iX加速器配备RapidArc技术实施照射。从剂量分布、实施效率、治疗照射参数等方面评价治疗计划质量的差异。对组间比较行配对t检验。结果宫颈癌采用Pinnacle设计的2Arc VMAT计划，在PTV的CI、直肠V30、V40和膀胱V30、V40略优于Eclipse，但PTV和PTV1的HI以及PTV，的CI上Eclipse则略优于Pinnacle（P〈0．05）。2Arc、3Arc的机器跳数上Eclipse系统均明显小于Pinnacle（P〈0．05）。前列腺癌采用Pinnacle TPS中1ArcVMAT计划，在PTV的HI、直肠V30、V40和膀胱V30、V40保护上略优于Eclipse TPS，但PTV的CI，Pinnacle则略劣于Eclipse（P〈0．05）。然而1Arc、2Arc机器跳数上Pinnacle和Eclipse间相近（P〉0．05）。结论对于宫颈癌和前列腺患者而言，两套商用TPS中VMAT治疗计划均能实现临床可接受的剂量分布。计划质量略有差异，但仍需更多的简单或复杂病例作进一步地研究以确定不同TPS实施VMAT优化的性能特点。

Tgfbr2 inactivation facilitates cellular plasticity and development of Pten-null prostate cancer

Mutations in tumors can create a state of increased cellular plasticity that promotes resistance to treatment. Thus, there is an urgent need to develop novel strategies for identifying key factors that regulate cellular plasticity in order to combat resistance to chemotherapy and radiation treatment. Here we report that prostate epithelial cell reprogramming could be exploited to identify key factors required for promoting prostate cancer tumorigenesis and cellular plasticity. Deletion of phosphatase and tensin homolog （Pten） and transforming growth factor-beta receptor type 2 （Tgfbr2） may increase prostate epithelial cell reprogramming efficiency in vitro and cause rapid tumor development and early mortality in vivo. Tgfbr2 ablation abolished TGF-β signaling but increased the bone morphogenetic protein （BMP） signaling pathway through the negative regulator Tmeff1. Furthermore, increased BMP signaling promotes expression of the tumor marker genes ID1, Oct4, Nanog, and Sox2; ID1/STAT3/NANOG expression was inversely correlated with patient survival. Thus, our findings provide information about the molecular mechanisms by which BMP signaling pathways render stemness capacity to prostate tumor cells.