Treatment planning comparison of high-dose-rate brachytherapy vs. robotic and conventional stereotactic body radiotherapy for ultrahypofractionated treatment of prostate cancer

Yasuo Yoshioka; Kazuma Sasamura; Makoto Ito; Masahiro Kaneko; Taro Takahashi; Wataru Anno; Nana Shimoyachi; Junji Suzuki; Takahito Okuda; Tairo Kashihara; Koji Inaba; Hiroshi Igaki; Jun Itami

doi:10.1016/j.phro.2023.100445

Treatment planning comparison of high-dose-rate brachytherapy vs. robotic and conventional stereotactic body radiotherapy for ultrahypofractionated treatment of prostate cancer

Phys Imaging Radiat Oncol. 2023 May 4:26:100445. doi: 10.1016/j.phro.2023.100445. eCollection 2023 Apr.

Authors

Yasuo Yoshioka^{1

2}, Kazuma Sasamura¹, Makoto Ito³, Masahiro Kaneko¹, Taro Takahashi¹, Wataru Anno¹, Nana Shimoyachi¹, Junji Suzuki⁴, Takahito Okuda², Tairo Kashihara⁵, Koji Inaba⁵, Hiroshi Igaki⁵, Jun Itami^{5

6}

Affiliations

¹ Department of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan.
² Department of Radiation Oncology, Toyota Memorial Hospital, Aichi, Japan.
³ Department of Radiology, Aichi Medical University Hospital, Aichi, Japan.
⁴ Radiotherapy Quality Management Group, Toyota Memorial Hospital, Aichi, Japan.
⁵ Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan.
⁶ Shin-Matsudo Accuracy Radiation Therapy Center, Shin-Matsudo Central General Hospital, Chiba, Japan.

Abstract

Background and purpose: Ultrahypofractionated radiation therapy is increasingly used in the treatment of prostate cancer. High-dose-rate brachytherapy (HDR-BT) and stereotactic body radiotherapy (SBRT) are representative methods of ultrahypofractionation. This study was performed to compare clinically applied treatment plans for patients who had been treated using HDR-BT vs. conventional or robotic SBRT.

Materials and methods: Calculated dose-volume indices between HDR-BT without a perirectal spacer (n = 20), robotic SBRT without a spacer (n = 40), and conventional (non-robotic) SBRT with a spacer (n = 40) were compared. Percentages against the prescription dose regarding the planning target volume (PTV), bladder, rectum, and urethra were statistically compared.

Results: The D50% of the PTV with HDR-BT (140.5% ± 4.9%) was significantly higher than that with robotic or conventional SBRT (116.2% ± 1.6%, 101.0% ± 0.4%, p < 0.01). The D2cm³ of the bladder with HDR-BT (65.6% ± 6.4%) was significantly lower than those with SBRT (105.3% ± 2.9%, 98.0% ± 1.3%, p < 0.01). The D2cm³ of the rectum with HDR-BT (60.6% ± 6.2%) was also significantly lower than those with SBRT (85.1% ± 8.8%, 70.4% ± 9.6%, p < 0.01). By contrast, the D0.1cm³ of the urethra with HDR-BT (117.1% ± 3.6%) was significantly higher than those with SBRT (100.2% ± 0.7%, 104.5% ± 0.6%, p < 0.01).

Conclusions: HDR-BT could administer a higher dose to the PTV and a lower dose to the bladder and rectum, at the cost of a slightly higher dose to the urethra compared with SBRT.

Keywords: High-dose-rate brachytherapy; Monotherapy; Prostate cancer; Stereotactic body radiation therapy; Ultrahypofractionation.