Neoadjuvent androgen deprivation for seminal vesicle reduction:The optimal portion of seminal vesicle included in the high-dose CTV in localized prostate cancer radiotherapy

Abstract

Abstract Purpose It is indicated by prostatectomy specimens that the proximal 1- to 2-cm seminal vesicles (SVs) be irradiated in radiotherapy for prostate cancer with intermediate- to high-risk factors. However, patients usually receive neo-adjuvant hormonal therapy (NHT) before radiotherapy. The purpose of this study is to clarify the length and volume reduction of SVs after NHT, and to help contour the optimal SV included into high-dose clinical target volume (CTV) for radiotherapy in intermediate- and high-risk patients. Methods and Materials: MR images both before and after NHT (5.3 ± 2.2 months) were collected from thirty-one patients with cT2-4N0M0 prostate cancer. SV volume was measured in axial T1WI, while SV length was obtained in a reconstructed oblique coronary plane through its long axial from a 3D sequence. Results SVs showed evident reduction both in length and volume (length: median 12.1%, range 4.0–28.0%, volume: median 39.9%, range 9.4%-66.2%). For SVs with and without MR detected involvement, length shortening were 16.7 ± 4.8% and 11.1 ± 4.4% (P < 0.001); for involved SVs and lesions within, volume reduction were 41.0 ± 16.0% and 66.3 ± 14.4% (P < 0.001), both indicating a more sensitive response to NHT of the involved portion than normal SV. Conclusion Both volume and length of the SV will reduce after receiving NHT. Besides, the invaded segments shrink more than normal SV tissue, indicating that SV portion included within the CTV can be reduced.