Impact of tumour invasion on seminal vesicles mobility in radiotherapy of prostate cancer.

Abstract

Mobility of the seminal vesicles relative to the prostate challenges adequate dose coverage. The aim of this study was to assess the impact of tumour invasion on SV mobility. Three groups of 30 prostate cancer patients with (1) no invasion on MR, (2) minimal invasion (<5mm), and (3) extensive invasion (>5mm) were studied. Translations and rotations of the SV were measured with CBCT and compared between the three groups. In the extensive group the random SV translations were significantly lower in comparison with the no invasion group in the LR: 0.15 vs 0.16 cm (p=0.015), CC: 0.17 vs 0.23 cm (p=0.004) and AP direction: 0.19 vs 0.26 cm (p=0.002). Also the random SV rotation on the LR axis was significantly lower: 5.2 vs 6.3° (p=0.035). In comparison with the minimal invasion group the random SV translations were significantly lower in the extensive group in the CC: 0.17 vs 0.24 cm (p=0.001) and AP direction 0.19 vs 0.31 cm (p=0.007) and for the rotation on the LR axis: 5.2 vs 6.5° (p=0.043). Increasing tumour invasion in the SV reduces the mobility of the SV, however the mobility remains considerable.