Radiotherapy for Clinically Localized T3b or T4 Very-High-Risk Prostate Cancer-Role of Dose Escalation Using High-Dose-Rate Brachytherapy Boost or High Dose Intensity Modulated Radiotherapy

Hideya Yamazaki; Gen Suzuki; Koji Masui; Norihiro Aibe; Daisuke Shimizu; Takuya Kimoto; Ken Yoshida; Satoaki Nakamura; Haruumi Okabe

doi:10.3390/cancers13081856

Radiotherapy for Clinically Localized T3b or T4 Very-High-Risk Prostate Cancer-Role of Dose Escalation Using High-Dose-Rate Brachytherapy Boost or High Dose Intensity Modulated Radiotherapy

Cancers (Basel). 2021 Apr 13;13(8):1856. doi: 10.3390/cancers13081856.

Authors

Hideya Yamazaki¹, Gen Suzuki¹, Koji Masui¹, Norihiro Aibe¹, Daisuke Shimizu¹, Takuya Kimoto¹, Ken Yoshida², Satoaki Nakamura², Haruumi Okabe³

Affiliations

¹ Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajiicho Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
² Department of Radiology, Kansai Medical University, Hirakata 573-1010, Japan.
³ Department of Radiology, Ujitakeda Hospital, Uji-City, Kyoto 611-0021, Japan.

Abstract

To examine the efficacy of dose escalating radiotherapy into patients with cT3b or T4 localized prostate cancer, we compared Group A (86 conventional dose external beam radiotherapy: EBRT group, treated with 70-72 Gy) and group B (39 high dose EBRT group (HDEBRT group, 74-80 Gy) and 124 high-dose-rate brachytherapy (HDR) + EBRT (HDR boost)) using multi-institutional retrospective data. The actuarial 5-year biochemical disease-free survival (bDFS) rate, prostate cancer specific survival rate (PSS), and overall survival rate (OS) were 75.8%, 96.8%, and 93.5%. Group B showed superior 5-year bDFS rate (81.2%) as compared to the group A (66.5%) (p < 0.0001) with a hazard ratio of 0.397. Equivocal 5-year PSS (98.3% and 94.8% in group B and group A) and OS (both 93.7%) were found between those groups. Accumulated late grade ≥ 2 toxicities in gastrointestinal and genitourinary tracts were similar among those three groups. Therefore, both HDEBRT and HDR boost could be good options for improving the bDFS rate in cT3-T4 localized prostate cancer without affecting PSS and OS.

Keywords: IMRT; T3b–T4; brachytherapy; high dose rate; prostate cancer; very high risk.