Studies Of Dosimetry Of Radiation Technology And Prediction Of Pathologic Stage For Prostate Cancer

Partâ… Dosimetry studies of different radiation therapy technology for prostate cancerObjective: To compare the dose distribution and dose-volume histograms (DVHs) of simultaneous modulated accelerated radiation therapy(SMART),three-dimensional conformal radiotherapy (3D- CRT) and conventional techniques of the planning target volume (PTV) and critical organs in prostate cancer treatment planning (include pelvic cavity prophylactic irradiation).Methods: A dosimetry study was carried out on five patients with prostate cancer with staging of T2-3N0M0. For each patient,three kinds of treatment planning were designed with a prescribed dose of 70Gy to 95%of PTV1( prostate and seminal vesicle) and 50Gy to 95%of PTV2(pelvic lymph node).The following parameters of these plans in each patient were compared:isodose distributions line,dose-volume histogram (DVH),V95%,Dmax,Dmin,Dmean, CI,HI of target volume and the dose of related critical organs.Results: SMART showed better dose uniformity and conformity than 3D-CRT and CRT and 3D-CRT was superior to conventional techniques except in PTV1(P<0.05 ) .SMART had advantage at sparing rectum and bladder compared with conventional techniques and 3DCRT(P<0.05). But the dose received by the intestine and colon were not significant different.Conclusion:Plans of SMART were superior to 3D-CRT and 3D-CRT plans were superior to conventional techniques considering the target volume and critical organs. SMART would appear to be the favored technique for prostate cancer radiation with regard to nodal treatment. Partâ…¡Studies of prediction of pathologic stage for prostate cancer2.1 Comparison of accuracy between the Partin Tables and Roach's formula to predict final pathological stage in prostate cancer in ChinaObjective: The study compared the predictive accuracy between the Partin tables of 1997 versions ,the Partin tables of 2007 versions and Roach's formula to predict final pathological stage in prostate cancer Chinese population.Methods: From January 2003 to September 2007,116 patients who have had radical retropubic prostatectomy was pathologically confirmed prostate adenocarcinoma in Shanghai 6th hospital. Serum PSA values, clinical stage, biopsy Gleason score were collected and Pathological features of the radical prostatectomy specimens were divided into organ confinement (OC), extraprostatic extension (EPE), seminal vesicle invasion (SVI) and lymph node involvement (LNI). 93 patients of them met 2007 Partin tables prediction selection criterion and 113 met 1997 Partin tables prediction selection criterion(Roach's formula likewise).Using vari-ous probability thresholds both Partin tables and Roach's formula was used to predict outcomes in each patient. Using different probability thresholds receiver operating characteristics (ROC) curves were then used to assess test performance.Results:Area under curve (AUC) of the 1997 Partin tables for OC, EPE, SVI and LNI was 0.834,0.605,0.716 and 0.808 and when using 2007 Partin table each AUC values was 0.786,0.613,0.666 and 0.811, respectively. AUC of Roach's formula for EPE, SVI and LNI was 0.495,0.712,0.754.Conclusion: Among the three predictive methods to predict pathological stage in prostate cancer,the predictive accuracy of 1997 Partin tables was the best . 2.2 The role of PSA subgroups and biopsy Gleason score in the prediction of pathologic stage in prostate cancerObjective: To evaluate the role of PSA subgroups and biopsy Gleason score in the prediction of pathologic stage.Methods: A total of 92 patients with pathologically confirmed prostate adenocarcinoma were retrospectively analysised in the study. All the patients underwent radical prostatectomy and had preoperative tPSA, free PSA,free PSA /total PSA(fPSA/tPSA),PSA density (PSAD) and biopsy Gleason score. Each of the above parameters in patients with organ-confined disease were compared with that in patients with extraprostatic extension ;The receiver operating characteristics (ROC) curve was used to analyze the performance of each of the above parameters to predict the pathologic stage;Multivariate logistic regression analysis was used to select the main influencing factor of organ-confined disease.Results:PSAD, tPSA, fPSA/tPSA and biopsy Gleason score levels were higher in patients with extraprostatic extension than that in patients with organ-confined disease(P<0.05); Only tPSA, PSAD can predict the pathologic stage of localized prostate cancer moderately in ROC curve analysis(area under curve (AUC)>0.7, P<0.05); Multivariate analysis revealed that only PSAD and biopsy Gleason score were the main influencing factor of organ-confined disease(P<0.05),and a multivariate model with them had AUC of 0.80 (P=0.000).Conclusion: PSAD was better than PSA in predicting organ-confined disease. Predictive models could consider use of PSAD instead of tPSA , and combine it with other factors to improve the predictive accuracy.