• Takuro Kainuma, Shogo Kawakami, Hideyasu Tsumura, Takefumi Satoh, TabataKen-IchiKIDepartment of Urology, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa, Japan., Masatsugu Iwamura, Kazushige Hayakawa, and Hiromichi Ishiyama.
• Department of Radiation Oncology, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa, Japan.
• Radiat Oncol. 2019 Sep 2; 14 (1): 158.

PurposeTo report results from our phase I dose-escalation study of stereotactic body radiotherapy (SBRT) using 4 fractions for patients with localized prostate cancer.Materials & MethodsFraction sizes of 8 Gy, 8.5 Gy, and 9 Gy were defined as levels 1, 2, and 3. The prescribed dose was delivered to at least 95% of the planning target volume. Image-guided, intensity-modulated radiotherapy was delivered to all patients. Dose-limiting toxicity (DLT) was defined as acute toxicity of Grade 3 or higher. The maximum tolerated dose (MTD) was defined as the level at which ≥30% of patients showed DLT. The recommended dose (RD) was defined to be one dose level below the MTD. If no patients at level 3 showed DLT, level 3 was defined as the recommended dose (RD).ResultsNine patients were enrolled in each level. All patients were low or intermediate risk. Median durations of follow-up for patients at levels 1-3 were 48.9 months, 42.6 months, and 18.4 months, respectively. Protocol treatment was completed for all patients. No patient showed DLT at each dose level. Level 3 was therefore designated as the RD for the phase II study. Although most toxicities were Grade 1, genitourinary toxicity was common compared to gastrointestinal toxicity. Three-year biochemical control rate was 90.3%.ConclusionThe dose level of 36 Gy in 4 fractions with a 2-day break was tolerable and highly encouraging for SBRT of localized prostate cancer. The phase II trial to confirm the efficacy and toxicity of this treatment is now on going.Trial RegistrationUMIN, UMIN000010236 . Registered 13 March 2013.

25 keywords...

hide…