Indications for and the significance of seminal vesicle irradiation during 3D conformal radiotherapy for XXXX .

@entity1 @entity137 @entity263 @entity1486
PURPOSE: To evaluate the use of pretreatment @entity1486 , Gleason score, and clinical stage as predictors of the risk of seminal vesicle involvement in @entity1 with clinically localized @entity263 , and to determine the impact of excluding the seminal vesicles on the dose received by surrounding normal tissues. METHODS AND MATERIALS: An empirically derived equation combining the preoperative @entity1486 and Gleason score was applied to 188 @entity1 treated with radical prostatectomy, for whom pathologic evaluation of the seminal vesicles was available. High and low risk groups for seminal vesicle involvement were defined using this equation. The observed risks of seminal vesicle involvement was compared to the predicted risk using the preoperative @entity1486 , Gleason score or clinical stage alone or using the empirical equation. Dose-volume histograms for five @entity1 treated using six-field conformal radiotherapy were compared including and excluding the seminal vesicles. RESULTS: Using the empirically derived equation, a low risk group of 109 @entity1 was identified with a calculated risk of seminal vesicle involvement of < or = 13% and an observed incidence of 7.3%. Among the high risk group of 79 @entity1 , which included all @entity1 with a calculated risk > 13%, 37% had seminal vesicle involvement (p < 0.001 low vs. high risk). Twenty percent of the rectal volume received on average above 86% of the total dose for the five plans which included the seminal vesicles compared to 68% for the five plans excluding the seminal vesicles. The doses to 40% of the rectal volume were 64% and 37% if the seminal vesicles were included and excluded, respectively. The dose to the bladder and femoral heads was also decreased but to a lesser extent. CONCLUSION: The empirical formula predicts risk of seminal vesicle involvement with a higher degree of significance for a larger number of @entity1 than either Gleason score, clinical stage, or @entity1486 alone. Based on an analysis of our first 100 @entity1 treated with definitive conformal therapy alone, approximately 47% of those @entity1 could have been treated excluding the seminal vesicles. Excluding the seminal vesicles may allow us to go to a higher total dose with less @entity137 .
